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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/tools/lguest
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/tools/lguest')
-rw-r--r--kernel/tools/lguest/.gitignore1
-rw-r--r--kernel/tools/lguest/Makefile13
-rw-r--r--kernel/tools/lguest/extract58
-rw-r--r--kernel/tools/lguest/lguest.c3410
-rw-r--r--kernel/tools/lguest/lguest.txt125
5 files changed, 3607 insertions, 0 deletions
diff --git a/kernel/tools/lguest/.gitignore b/kernel/tools/lguest/.gitignore
new file mode 100644
index 000000000..115587fd5
--- /dev/null
+++ b/kernel/tools/lguest/.gitignore
@@ -0,0 +1 @@
+lguest
diff --git a/kernel/tools/lguest/Makefile b/kernel/tools/lguest/Makefile
new file mode 100644
index 000000000..a107b5e4d
--- /dev/null
+++ b/kernel/tools/lguest/Makefile
@@ -0,0 +1,13 @@
+# This creates the demonstration utility "lguest" which runs a Linux guest.
+CFLAGS:=-m32 -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -U_FORTIFY_SOURCE -Iinclude
+
+all: lguest
+
+include/linux/virtio_types.h: ../../include/uapi/linux/virtio_types.h
+ mkdir -p include/linux 2>&1 || true
+ ln -sf ../../../../include/uapi/linux/virtio_types.h $@
+
+lguest: include/linux/virtio_types.h
+
+clean:
+ rm -f lguest
diff --git a/kernel/tools/lguest/extract b/kernel/tools/lguest/extract
new file mode 100644
index 000000000..7730bb6e4
--- /dev/null
+++ b/kernel/tools/lguest/extract
@@ -0,0 +1,58 @@
+#! /bin/sh
+
+set -e
+
+PREFIX=$1
+shift
+
+trap 'rm -r $TMPDIR' 0
+TMPDIR=`mktemp -d`
+
+exec 3>/dev/null
+for f; do
+ while IFS="
+" read -r LINE; do
+ case "$LINE" in
+ *$PREFIX:[0-9]*:\**)
+ NUM=`echo "$LINE" | sed "s/.*$PREFIX:\([0-9]*\).*/\1/"`
+ if [ -f $TMPDIR/$NUM ]; then
+ echo "$TMPDIR/$NUM already exits prior to $f"
+ exit 1
+ fi
+ exec 3>>$TMPDIR/$NUM
+ echo $f | sed 's,\.\./,,g' > $TMPDIR/.$NUM
+ /bin/echo "$LINE" | sed -e "s/$PREFIX:[0-9]*//" -e "s/:\*/*/" >&3
+ ;;
+ *$PREFIX:[0-9]*)
+ NUM=`echo "$LINE" | sed "s/.*$PREFIX:\([0-9]*\).*/\1/"`
+ if [ -f $TMPDIR/$NUM ]; then
+ echo "$TMPDIR/$NUM already exits prior to $f"
+ exit 1
+ fi
+ exec 3>>$TMPDIR/$NUM
+ echo $f | sed 's,\.\./,,g' > $TMPDIR/.$NUM
+ /bin/echo "$LINE" | sed "s/$PREFIX:[0-9]*//" >&3
+ ;;
+ *:\**)
+ /bin/echo "$LINE" | sed -e "s/:\*/*/" -e "s,/\*\*/,," >&3
+ echo >&3
+ exec 3>/dev/null
+ ;;
+ *)
+ /bin/echo "$LINE" >&3
+ ;;
+ esac
+ done < $f
+ echo >&3
+ exec 3>/dev/null
+done
+
+LASTFILE=""
+for f in $TMPDIR/*; do
+ if [ "$LASTFILE" != $(cat $TMPDIR/.$(basename $f) ) ]; then
+ LASTFILE=$(cat $TMPDIR/.$(basename $f) )
+ echo "[ $LASTFILE ]"
+ fi
+ cat $f
+done
+
diff --git a/kernel/tools/lguest/lguest.c b/kernel/tools/lguest/lguest.c
new file mode 100644
index 000000000..e44052483
--- /dev/null
+++ b/kernel/tools/lguest/lguest.c
@@ -0,0 +1,3410 @@
+/*P:100
+ * This is the Launcher code, a simple program which lays out the "physical"
+ * memory for the new Guest by mapping the kernel image and the virtual
+ * devices, then opens /dev/lguest to tell the kernel about the Guest and
+ * control it.
+:*/
+#define _LARGEFILE64_SOURCE
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <err.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <elf.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <sys/eventfd.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <ctype.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+#include <time.h>
+#include <netinet/in.h>
+#include <net/if.h>
+#include <linux/sockios.h>
+#include <linux/if_tun.h>
+#include <sys/uio.h>
+#include <termios.h>
+#include <getopt.h>
+#include <assert.h>
+#include <sched.h>
+#include <limits.h>
+#include <stddef.h>
+#include <signal.h>
+#include <pwd.h>
+#include <grp.h>
+#include <sys/user.h>
+#include <linux/pci_regs.h>
+
+#ifndef VIRTIO_F_ANY_LAYOUT
+#define VIRTIO_F_ANY_LAYOUT 27
+#endif
+
+/*L:110
+ * We can ignore the 43 include files we need for this program, but I do want
+ * to draw attention to the use of kernel-style types.
+ *
+ * As Linus said, "C is a Spartan language, and so should your naming be." I
+ * like these abbreviations, so we define them here. Note that u64 is always
+ * unsigned long long, which works on all Linux systems: this means that we can
+ * use %llu in printf for any u64.
+ */
+typedef unsigned long long u64;
+typedef uint32_t u32;
+typedef uint16_t u16;
+typedef uint8_t u8;
+/*:*/
+
+#define VIRTIO_CONFIG_NO_LEGACY
+#define VIRTIO_PCI_NO_LEGACY
+#define VIRTIO_BLK_NO_LEGACY
+#define VIRTIO_NET_NO_LEGACY
+
+/* Use in-kernel ones, which defines VIRTIO_F_VERSION_1 */
+#include "../../include/uapi/linux/virtio_config.h"
+#include "../../include/uapi/linux/virtio_net.h"
+#include "../../include/uapi/linux/virtio_blk.h"
+#include "../../include/uapi/linux/virtio_console.h"
+#include "../../include/uapi/linux/virtio_rng.h"
+#include <linux/virtio_ring.h>
+#include "../../include/uapi/linux/virtio_pci.h"
+#include <asm/bootparam.h>
+#include "../../include/linux/lguest_launcher.h"
+
+#define BRIDGE_PFX "bridge:"
+#ifndef SIOCBRADDIF
+#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
+#endif
+/* We can have up to 256 pages for devices. */
+#define DEVICE_PAGES 256
+/* This will occupy 3 pages: it must be a power of 2. */
+#define VIRTQUEUE_NUM 256
+
+/*L:120
+ * verbose is both a global flag and a macro. The C preprocessor allows
+ * this, and although I wouldn't recommend it, it works quite nicely here.
+ */
+static bool verbose;
+#define verbose(args...) \
+ do { if (verbose) printf(args); } while(0)
+/*:*/
+
+/* The pointer to the start of guest memory. */
+static void *guest_base;
+/* The maximum guest physical address allowed, and maximum possible. */
+static unsigned long guest_limit, guest_max, guest_mmio;
+/* The /dev/lguest file descriptor. */
+static int lguest_fd;
+
+/* a per-cpu variable indicating whose vcpu is currently running */
+static unsigned int __thread cpu_id;
+
+/* 5 bit device number in the PCI_CONFIG_ADDR => 32 only */
+#define MAX_PCI_DEVICES 32
+
+/* This is our list of devices. */
+struct device_list {
+ /* Counter to assign interrupt numbers. */
+ unsigned int next_irq;
+
+ /* Counter to print out convenient device numbers. */
+ unsigned int device_num;
+
+ /* PCI devices. */
+ struct device *pci[MAX_PCI_DEVICES];
+};
+
+/* The list of Guest devices, based on command line arguments. */
+static struct device_list devices;
+
+struct virtio_pci_cfg_cap {
+ struct virtio_pci_cap cap;
+ u32 pci_cfg_data; /* Data for BAR access. */
+};
+
+struct virtio_pci_mmio {
+ struct virtio_pci_common_cfg cfg;
+ u16 notify;
+ u8 isr;
+ u8 padding;
+ /* Device-specific configuration follows this. */
+};
+
+/* This is the layout (little-endian) of the PCI config space. */
+struct pci_config {
+ u16 vendor_id, device_id;
+ u16 command, status;
+ u8 revid, prog_if, subclass, class;
+ u8 cacheline_size, lat_timer, header_type, bist;
+ u32 bar[6];
+ u32 cardbus_cis_ptr;
+ u16 subsystem_vendor_id, subsystem_device_id;
+ u32 expansion_rom_addr;
+ u8 capabilities, reserved1[3];
+ u32 reserved2;
+ u8 irq_line, irq_pin, min_grant, max_latency;
+
+ /* Now, this is the linked capability list. */
+ struct virtio_pci_cap common;
+ struct virtio_pci_notify_cap notify;
+ struct virtio_pci_cap isr;
+ struct virtio_pci_cap device;
+ struct virtio_pci_cfg_cap cfg_access;
+};
+
+/* The device structure describes a single device. */
+struct device {
+ /* The name of this device, for --verbose. */
+ const char *name;
+
+ /* Any queues attached to this device */
+ struct virtqueue *vq;
+
+ /* Is it operational */
+ bool running;
+
+ /* Has it written FEATURES_OK but not re-checked it? */
+ bool wrote_features_ok;
+
+ /* PCI configuration */
+ union {
+ struct pci_config config;
+ u32 config_words[sizeof(struct pci_config) / sizeof(u32)];
+ };
+
+ /* Features we offer, and those accepted. */
+ u64 features, features_accepted;
+
+ /* Device-specific config hangs off the end of this. */
+ struct virtio_pci_mmio *mmio;
+
+ /* PCI MMIO resources (all in BAR0) */
+ size_t mmio_size;
+ u32 mmio_addr;
+
+ /* Device-specific data. */
+ void *priv;
+};
+
+/* The virtqueue structure describes a queue attached to a device. */
+struct virtqueue {
+ struct virtqueue *next;
+
+ /* Which device owns me. */
+ struct device *dev;
+
+ /* Name for printing errors. */
+ const char *name;
+
+ /* The actual ring of buffers. */
+ struct vring vring;
+
+ /* The information about this virtqueue (we only use queue_size on) */
+ struct virtio_pci_common_cfg pci_config;
+
+ /* Last available index we saw. */
+ u16 last_avail_idx;
+
+ /* How many are used since we sent last irq? */
+ unsigned int pending_used;
+
+ /* Eventfd where Guest notifications arrive. */
+ int eventfd;
+
+ /* Function for the thread which is servicing this virtqueue. */
+ void (*service)(struct virtqueue *vq);
+ pid_t thread;
+};
+
+/* Remember the arguments to the program so we can "reboot" */
+static char **main_args;
+
+/* The original tty settings to restore on exit. */
+static struct termios orig_term;
+
+/*
+ * We have to be careful with barriers: our devices are all run in separate
+ * threads and so we need to make sure that changes visible to the Guest happen
+ * in precise order.
+ */
+#define wmb() __asm__ __volatile__("" : : : "memory")
+#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
+#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
+
+/* Wrapper for the last available index. Makes it easier to change. */
+#define lg_last_avail(vq) ((vq)->last_avail_idx)
+
+/*
+ * The virtio configuration space is defined to be little-endian. x86 is
+ * little-endian too, but it's nice to be explicit so we have these helpers.
+ */
+#define cpu_to_le16(v16) (v16)
+#define cpu_to_le32(v32) (v32)
+#define cpu_to_le64(v64) (v64)
+#define le16_to_cpu(v16) (v16)
+#define le32_to_cpu(v32) (v32)
+#define le64_to_cpu(v64) (v64)
+
+/*
+ * A real device would ignore weird/non-compliant driver behaviour. We
+ * stop and flag it, to help debugging Linux problems.
+ */
+#define bad_driver(d, fmt, ...) \
+ errx(1, "%s: bad driver: " fmt, (d)->name, ## __VA_ARGS__)
+#define bad_driver_vq(vq, fmt, ...) \
+ errx(1, "%s vq %s: bad driver: " fmt, (vq)->dev->name, \
+ vq->name, ## __VA_ARGS__)
+
+/* Is this iovec empty? */
+static bool iov_empty(const struct iovec iov[], unsigned int num_iov)
+{
+ unsigned int i;
+
+ for (i = 0; i < num_iov; i++)
+ if (iov[i].iov_len)
+ return false;
+ return true;
+}
+
+/* Take len bytes from the front of this iovec. */
+static void iov_consume(struct device *d,
+ struct iovec iov[], unsigned num_iov,
+ void *dest, unsigned len)
+{
+ unsigned int i;
+
+ for (i = 0; i < num_iov; i++) {
+ unsigned int used;
+
+ used = iov[i].iov_len < len ? iov[i].iov_len : len;
+ if (dest) {
+ memcpy(dest, iov[i].iov_base, used);
+ dest += used;
+ }
+ iov[i].iov_base += used;
+ iov[i].iov_len -= used;
+ len -= used;
+ }
+ if (len != 0)
+ bad_driver(d, "iovec too short!");
+}
+
+/*L:100
+ * The Launcher code itself takes us out into userspace, that scary place where
+ * pointers run wild and free! Unfortunately, like most userspace programs,
+ * it's quite boring (which is why everyone likes to hack on the kernel!).
+ * Perhaps if you make up an Lguest Drinking Game at this point, it will get
+ * you through this section. Or, maybe not.
+ *
+ * The Launcher sets up a big chunk of memory to be the Guest's "physical"
+ * memory and stores it in "guest_base". In other words, Guest physical ==
+ * Launcher virtual with an offset.
+ *
+ * This can be tough to get your head around, but usually it just means that we
+ * use these trivial conversion functions when the Guest gives us its
+ * "physical" addresses:
+ */
+static void *from_guest_phys(unsigned long addr)
+{
+ return guest_base + addr;
+}
+
+static unsigned long to_guest_phys(const void *addr)
+{
+ return (addr - guest_base);
+}
+
+/*L:130
+ * Loading the Kernel.
+ *
+ * We start with couple of simple helper routines. open_or_die() avoids
+ * error-checking code cluttering the callers:
+ */
+static int open_or_die(const char *name, int flags)
+{
+ int fd = open(name, flags);
+ if (fd < 0)
+ err(1, "Failed to open %s", name);
+ return fd;
+}
+
+/* map_zeroed_pages() takes a number of pages. */
+static void *map_zeroed_pages(unsigned int num)
+{
+ int fd = open_or_die("/dev/zero", O_RDONLY);
+ void *addr;
+
+ /*
+ * We use a private mapping (ie. if we write to the page, it will be
+ * copied). We allocate an extra two pages PROT_NONE to act as guard
+ * pages against read/write attempts that exceed allocated space.
+ */
+ addr = mmap(NULL, getpagesize() * (num+2),
+ PROT_NONE, MAP_PRIVATE, fd, 0);
+
+ if (addr == MAP_FAILED)
+ err(1, "Mmapping %u pages of /dev/zero", num);
+
+ if (mprotect(addr + getpagesize(), getpagesize() * num,
+ PROT_READ|PROT_WRITE) == -1)
+ err(1, "mprotect rw %u pages failed", num);
+
+ /*
+ * One neat mmap feature is that you can close the fd, and it
+ * stays mapped.
+ */
+ close(fd);
+
+ /* Return address after PROT_NONE page */
+ return addr + getpagesize();
+}
+
+/* Get some bytes which won't be mapped into the guest. */
+static unsigned long get_mmio_region(size_t size)
+{
+ unsigned long addr = guest_mmio;
+ size_t i;
+
+ if (!size)
+ return addr;
+
+ /* Size has to be a power of 2 (and multiple of 16) */
+ for (i = 1; i < size; i <<= 1);
+
+ guest_mmio += i;
+
+ return addr;
+}
+
+/*
+ * This routine is used to load the kernel or initrd. It tries mmap, but if
+ * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
+ * it falls back to reading the memory in.
+ */
+static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
+{
+ ssize_t r;
+
+ /*
+ * We map writable even though for some segments are marked read-only.
+ * The kernel really wants to be writable: it patches its own
+ * instructions.
+ *
+ * MAP_PRIVATE means that the page won't be copied until a write is
+ * done to it. This allows us to share untouched memory between
+ * Guests.
+ */
+ if (mmap(addr, len, PROT_READ|PROT_WRITE,
+ MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED)
+ return;
+
+ /* pread does a seek and a read in one shot: saves a few lines. */
+ r = pread(fd, addr, len, offset);
+ if (r != len)
+ err(1, "Reading offset %lu len %lu gave %zi", offset, len, r);
+}
+
+/*
+ * This routine takes an open vmlinux image, which is in ELF, and maps it into
+ * the Guest memory. ELF = Embedded Linking Format, which is the format used
+ * by all modern binaries on Linux including the kernel.
+ *
+ * The ELF headers give *two* addresses: a physical address, and a virtual
+ * address. We use the physical address; the Guest will map itself to the
+ * virtual address.
+ *
+ * We return the starting address.
+ */
+static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
+{
+ Elf32_Phdr phdr[ehdr->e_phnum];
+ unsigned int i;
+
+ /*
+ * Sanity checks on the main ELF header: an x86 executable with a
+ * reasonable number of correctly-sized program headers.
+ */
+ if (ehdr->e_type != ET_EXEC
+ || ehdr->e_machine != EM_386
+ || ehdr->e_phentsize != sizeof(Elf32_Phdr)
+ || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
+ errx(1, "Malformed elf header");
+
+ /*
+ * An ELF executable contains an ELF header and a number of "program"
+ * headers which indicate which parts ("segments") of the program to
+ * load where.
+ */
+
+ /* We read in all the program headers at once: */
+ if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
+ err(1, "Seeking to program headers");
+ if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
+ err(1, "Reading program headers");
+
+ /*
+ * Try all the headers: there are usually only three. A read-only one,
+ * a read-write one, and a "note" section which we don't load.
+ */
+ for (i = 0; i < ehdr->e_phnum; i++) {
+ /* If this isn't a loadable segment, we ignore it */
+ if (phdr[i].p_type != PT_LOAD)
+ continue;
+
+ verbose("Section %i: size %i addr %p\n",
+ i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
+
+ /* We map this section of the file at its physical address. */
+ map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
+ phdr[i].p_offset, phdr[i].p_filesz);
+ }
+
+ /* The entry point is given in the ELF header. */
+ return ehdr->e_entry;
+}
+
+/*L:150
+ * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed
+ * to jump into it and it will unpack itself. We used to have to perform some
+ * hairy magic because the unpacking code scared me.
+ *
+ * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote
+ * a small patch to jump over the tricky bits in the Guest, so now we just read
+ * the funky header so we know where in the file to load, and away we go!
+ */
+static unsigned long load_bzimage(int fd)
+{
+ struct boot_params boot;
+ int r;
+ /* Modern bzImages get loaded at 1M. */
+ void *p = from_guest_phys(0x100000);
+
+ /*
+ * Go back to the start of the file and read the header. It should be
+ * a Linux boot header (see Documentation/x86/boot.txt)
+ */
+ lseek(fd, 0, SEEK_SET);
+ read(fd, &boot, sizeof(boot));
+
+ /* Inside the setup_hdr, we expect the magic "HdrS" */
+ if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
+ errx(1, "This doesn't look like a bzImage to me");
+
+ /* Skip over the extra sectors of the header. */
+ lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
+
+ /* Now read everything into memory. in nice big chunks. */
+ while ((r = read(fd, p, 65536)) > 0)
+ p += r;
+
+ /* Finally, code32_start tells us where to enter the kernel. */
+ return boot.hdr.code32_start;
+}
+
+/*L:140
+ * Loading the kernel is easy when it's a "vmlinux", but most kernels
+ * come wrapped up in the self-decompressing "bzImage" format. With a little
+ * work, we can load those, too.
+ */
+static unsigned long load_kernel(int fd)
+{
+ Elf32_Ehdr hdr;
+
+ /* Read in the first few bytes. */
+ if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
+ err(1, "Reading kernel");
+
+ /* If it's an ELF file, it starts with "\177ELF" */
+ if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
+ return map_elf(fd, &hdr);
+
+ /* Otherwise we assume it's a bzImage, and try to load it. */
+ return load_bzimage(fd);
+}
+
+/*
+ * This is a trivial little helper to align pages. Andi Kleen hated it because
+ * it calls getpagesize() twice: "it's dumb code."
+ *
+ * Kernel guys get really het up about optimization, even when it's not
+ * necessary. I leave this code as a reaction against that.
+ */
+static inline unsigned long page_align(unsigned long addr)
+{
+ /* Add upwards and truncate downwards. */
+ return ((addr + getpagesize()-1) & ~(getpagesize()-1));
+}
+
+/*L:180
+ * An "initial ram disk" is a disk image loaded into memory along with the
+ * kernel which the kernel can use to boot from without needing any drivers.
+ * Most distributions now use this as standard: the initrd contains the code to
+ * load the appropriate driver modules for the current machine.
+ *
+ * Importantly, James Morris works for RedHat, and Fedora uses initrds for its
+ * kernels. He sent me this (and tells me when I break it).
+ */
+static unsigned long load_initrd(const char *name, unsigned long mem)
+{
+ int ifd;
+ struct stat st;
+ unsigned long len;
+
+ ifd = open_or_die(name, O_RDONLY);
+ /* fstat() is needed to get the file size. */
+ if (fstat(ifd, &st) < 0)
+ err(1, "fstat() on initrd '%s'", name);
+
+ /*
+ * We map the initrd at the top of memory, but mmap wants it to be
+ * page-aligned, so we round the size up for that.
+ */
+ len = page_align(st.st_size);
+ map_at(ifd, from_guest_phys(mem - len), 0, st.st_size);
+ /*
+ * Once a file is mapped, you can close the file descriptor. It's a
+ * little odd, but quite useful.
+ */
+ close(ifd);
+ verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len);
+
+ /* We return the initrd size. */
+ return len;
+}
+/*:*/
+
+/*
+ * Simple routine to roll all the commandline arguments together with spaces
+ * between them.
+ */
+static void concat(char *dst, char *args[])
+{
+ unsigned int i, len = 0;
+
+ for (i = 0; args[i]; i++) {
+ if (i) {
+ strcat(dst+len, " ");
+ len++;
+ }
+ strcpy(dst+len, args[i]);
+ len += strlen(args[i]);
+ }
+ /* In case it's empty. */
+ dst[len] = '\0';
+}
+
+/*L:185
+ * This is where we actually tell the kernel to initialize the Guest. We
+ * saw the arguments it expects when we looked at initialize() in lguest_user.c:
+ * the base of Guest "physical" memory, the top physical page to allow and the
+ * entry point for the Guest.
+ */
+static void tell_kernel(unsigned long start)
+{
+ unsigned long args[] = { LHREQ_INITIALIZE,
+ (unsigned long)guest_base,
+ guest_limit / getpagesize(), start,
+ (guest_mmio+getpagesize()-1) / getpagesize() };
+ verbose("Guest: %p - %p (%#lx, MMIO %#lx)\n",
+ guest_base, guest_base + guest_limit,
+ guest_limit, guest_mmio);
+ lguest_fd = open_or_die("/dev/lguest", O_RDWR);
+ if (write(lguest_fd, args, sizeof(args)) < 0)
+ err(1, "Writing to /dev/lguest");
+}
+/*:*/
+
+/*L:200
+ * Device Handling.
+ *
+ * When the Guest gives us a buffer, it sends an array of addresses and sizes.
+ * We need to make sure it's not trying to reach into the Launcher itself, so
+ * we have a convenient routine which checks it and exits with an error message
+ * if something funny is going on:
+ */
+static void *_check_pointer(struct device *d,
+ unsigned long addr, unsigned int size,
+ unsigned int line)
+{
+ /*
+ * Check if the requested address and size exceeds the allocated memory,
+ * or addr + size wraps around.
+ */
+ if ((addr + size) > guest_limit || (addr + size) < addr)
+ bad_driver(d, "%s:%i: Invalid address %#lx",
+ __FILE__, line, addr);
+ /*
+ * We return a pointer for the caller's convenience, now we know it's
+ * safe to use.
+ */
+ return from_guest_phys(addr);
+}
+/* A macro which transparently hands the line number to the real function. */
+#define check_pointer(d,addr,size) _check_pointer(d, addr, size, __LINE__)
+
+/*
+ * Each buffer in the virtqueues is actually a chain of descriptors. This
+ * function returns the next descriptor in the chain, or vq->vring.num if we're
+ * at the end.
+ */
+static unsigned next_desc(struct device *d, struct vring_desc *desc,
+ unsigned int i, unsigned int max)
+{
+ unsigned int next;
+
+ /* If this descriptor says it doesn't chain, we're done. */
+ if (!(desc[i].flags & VRING_DESC_F_NEXT))
+ return max;
+
+ /* Check they're not leading us off end of descriptors. */
+ next = desc[i].next;
+ /* Make sure compiler knows to grab that: we don't want it changing! */
+ wmb();
+
+ if (next >= max)
+ bad_driver(d, "Desc next is %u", next);
+
+ return next;
+}
+
+/*
+ * This actually sends the interrupt for this virtqueue, if we've used a
+ * buffer.
+ */
+static void trigger_irq(struct virtqueue *vq)
+{
+ unsigned long buf[] = { LHREQ_IRQ, vq->dev->config.irq_line };
+
+ /* Don't inform them if nothing used. */
+ if (!vq->pending_used)
+ return;
+ vq->pending_used = 0;
+
+ /*
+ * 2.4.7.1:
+ *
+ * If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
+ * The driver MUST set flags to 0 or 1.
+ */
+ if (vq->vring.avail->flags > 1)
+ bad_driver_vq(vq, "avail->flags = %u\n", vq->vring.avail->flags);
+
+ /*
+ * 2.4.7.2:
+ *
+ * If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
+ *
+ * - The device MUST ignore the used_event value.
+ * - After the device writes a descriptor index into the used ring:
+ * - If flags is 1, the device SHOULD NOT send an interrupt.
+ * - If flags is 0, the device MUST send an interrupt.
+ */
+ if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
+ return;
+ }
+
+ /*
+ * 4.1.4.5.1:
+ *
+ * If MSI-X capability is disabled, the device MUST set the Queue
+ * Interrupt bit in ISR status before sending a virtqueue notification
+ * to the driver.
+ */
+ vq->dev->mmio->isr = 0x1;
+
+ /* Send the Guest an interrupt tell them we used something up. */
+ if (write(lguest_fd, buf, sizeof(buf)) != 0)
+ err(1, "Triggering irq %i", vq->dev->config.irq_line);
+}
+
+/*
+ * This looks in the virtqueue for the first available buffer, and converts
+ * it to an iovec for convenient access. Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function waits if necessary, and returns the descriptor number found.
+ */
+static unsigned wait_for_vq_desc(struct virtqueue *vq,
+ struct iovec iov[],
+ unsigned int *out_num, unsigned int *in_num)
+{
+ unsigned int i, head, max;
+ struct vring_desc *desc;
+ u16 last_avail = lg_last_avail(vq);
+
+ /*
+ * 2.4.7.1:
+ *
+ * The driver MUST handle spurious interrupts from the device.
+ *
+ * That's why this is a while loop.
+ */
+
+ /* There's nothing available? */
+ while (last_avail == vq->vring.avail->idx) {
+ u64 event;
+
+ /*
+ * Since we're about to sleep, now is a good time to tell the
+ * Guest about what we've used up to now.
+ */
+ trigger_irq(vq);
+
+ /* OK, now we need to know about added descriptors. */
+ vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
+
+ /*
+ * They could have slipped one in as we were doing that: make
+ * sure it's written, then check again.
+ */
+ mb();
+ if (last_avail != vq->vring.avail->idx) {
+ vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
+ break;
+ }
+
+ /* Nothing new? Wait for eventfd to tell us they refilled. */
+ if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
+ errx(1, "Event read failed?");
+
+ /* We don't need to be notified again. */
+ vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
+ }
+
+ /* Check it isn't doing very strange things with descriptor numbers. */
+ if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
+ bad_driver_vq(vq, "Guest moved used index from %u to %u",
+ last_avail, vq->vring.avail->idx);
+
+ /*
+ * Make sure we read the descriptor number *after* we read the ring
+ * update; don't let the cpu or compiler change the order.
+ */
+ rmb();
+
+ /*
+ * Grab the next descriptor number they're advertising, and increment
+ * the index we've seen.
+ */
+ head = vq->vring.avail->ring[last_avail % vq->vring.num];
+ lg_last_avail(vq)++;
+
+ /* If their number is silly, that's a fatal mistake. */
+ if (head >= vq->vring.num)
+ bad_driver_vq(vq, "Guest says index %u is available", head);
+
+ /* When we start there are none of either input nor output. */
+ *out_num = *in_num = 0;
+
+ max = vq->vring.num;
+ desc = vq->vring.desc;
+ i = head;
+
+ /*
+ * We have to read the descriptor after we read the descriptor number,
+ * but there's a data dependency there so the CPU shouldn't reorder
+ * that: no rmb() required.
+ */
+
+ do {
+ /*
+ * If this is an indirect entry, then this buffer contains a
+ * descriptor table which we handle as if it's any normal
+ * descriptor chain.
+ */
+ if (desc[i].flags & VRING_DESC_F_INDIRECT) {
+ /* 2.4.5.3.1:
+ *
+ * The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
+ * flag unless the VIRTIO_F_INDIRECT_DESC feature was
+ * negotiated.
+ */
+ if (!(vq->dev->features_accepted &
+ (1<<VIRTIO_RING_F_INDIRECT_DESC)))
+ bad_driver_vq(vq, "vq indirect not negotiated");
+
+ /*
+ * 2.4.5.3.1:
+ *
+ * The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
+ * flag within an indirect descriptor (ie. only one
+ * table per descriptor).
+ */
+ if (desc != vq->vring.desc)
+ bad_driver_vq(vq, "Indirect within indirect");
+
+ /*
+ * Proposed update VIRTIO-134 spells this out:
+ *
+ * A driver MUST NOT set both VIRTQ_DESC_F_INDIRECT
+ * and VIRTQ_DESC_F_NEXT in flags.
+ */
+ if (desc[i].flags & VRING_DESC_F_NEXT)
+ bad_driver_vq(vq, "indirect and next together");
+
+ if (desc[i].len % sizeof(struct vring_desc))
+ bad_driver_vq(vq,
+ "Invalid size for indirect table");
+ /*
+ * 2.4.5.3.2:
+ *
+ * The device MUST ignore the write-only flag
+ * (flags&VIRTQ_DESC_F_WRITE) in the descriptor that
+ * refers to an indirect table.
+ *
+ * We ignore it here: :)
+ */
+
+ max = desc[i].len / sizeof(struct vring_desc);
+ desc = check_pointer(vq->dev, desc[i].addr, desc[i].len);
+ i = 0;
+
+ /* 2.4.5.3.1:
+ *
+ * A driver MUST NOT create a descriptor chain longer
+ * than the Queue Size of the device.
+ */
+ if (max > vq->pci_config.queue_size)
+ bad_driver_vq(vq,
+ "indirect has too many entries");
+ }
+
+ /* Grab the first descriptor, and check it's OK. */
+ iov[*out_num + *in_num].iov_len = desc[i].len;
+ iov[*out_num + *in_num].iov_base
+ = check_pointer(vq->dev, desc[i].addr, desc[i].len);
+ /* If this is an input descriptor, increment that count. */
+ if (desc[i].flags & VRING_DESC_F_WRITE)
+ (*in_num)++;
+ else {
+ /*
+ * If it's an output descriptor, they're all supposed
+ * to come before any input descriptors.
+ */
+ if (*in_num)
+ bad_driver_vq(vq,
+ "Descriptor has out after in");
+ (*out_num)++;
+ }
+
+ /* If we've got too many, that implies a descriptor loop. */
+ if (*out_num + *in_num > max)
+ bad_driver_vq(vq, "Looped descriptor");
+ } while ((i = next_desc(vq->dev, desc, i, max)) != max);
+
+ return head;
+}
+
+/*
+ * After we've used one of their buffers, we tell the Guest about it. Sometime
+ * later we'll want to send them an interrupt using trigger_irq(); note that
+ * wait_for_vq_desc() does that for us if it has to wait.
+ */
+static void add_used(struct virtqueue *vq, unsigned int head, int len)
+{
+ struct vring_used_elem *used;
+
+ /*
+ * The virtqueue contains a ring of used buffers. Get a pointer to the
+ * next entry in that used ring.
+ */
+ used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
+ used->id = head;
+ used->len = len;
+ /* Make sure buffer is written before we update index. */
+ wmb();
+ vq->vring.used->idx++;
+ vq->pending_used++;
+}
+
+/* And here's the combo meal deal. Supersize me! */
+static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len)
+{
+ add_used(vq, head, len);
+ trigger_irq(vq);
+}
+
+/*
+ * The Console
+ *
+ * We associate some data with the console for our exit hack.
+ */
+struct console_abort {
+ /* How many times have they hit ^C? */
+ int count;
+ /* When did they start? */
+ struct timeval start;
+};
+
+/* This is the routine which handles console input (ie. stdin). */
+static void console_input(struct virtqueue *vq)
+{
+ int len;
+ unsigned int head, in_num, out_num;
+ struct console_abort *abort = vq->dev->priv;
+ struct iovec iov[vq->vring.num];
+
+ /* Make sure there's a descriptor available. */
+ head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
+ if (out_num)
+ bad_driver_vq(vq, "Output buffers in console in queue?");
+
+ /* Read into it. This is where we usually wait. */
+ len = readv(STDIN_FILENO, iov, in_num);
+ if (len <= 0) {
+ /* Ran out of input? */
+ warnx("Failed to get console input, ignoring console.");
+ /*
+ * For simplicity, dying threads kill the whole Launcher. So
+ * just nap here.
+ */
+ for (;;)
+ pause();
+ }
+
+ /* Tell the Guest we used a buffer. */
+ add_used_and_trigger(vq, head, len);
+
+ /*
+ * Three ^C within one second? Exit.
+ *
+ * This is such a hack, but works surprisingly well. Each ^C has to
+ * be in a buffer by itself, so they can't be too fast. But we check
+ * that we get three within about a second, so they can't be too
+ * slow.
+ */
+ if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) {
+ abort->count = 0;
+ return;
+ }
+
+ abort->count++;
+ if (abort->count == 1)
+ gettimeofday(&abort->start, NULL);
+ else if (abort->count == 3) {
+ struct timeval now;
+ gettimeofday(&now, NULL);
+ /* Kill all Launcher processes with SIGINT, like normal ^C */
+ if (now.tv_sec <= abort->start.tv_sec+1)
+ kill(0, SIGINT);
+ abort->count = 0;
+ }
+}
+
+/* This is the routine which handles console output (ie. stdout). */
+static void console_output(struct virtqueue *vq)
+{
+ unsigned int head, out, in;
+ struct iovec iov[vq->vring.num];
+
+ /* We usually wait in here, for the Guest to give us something. */
+ head = wait_for_vq_desc(vq, iov, &out, &in);
+ if (in)
+ bad_driver_vq(vq, "Input buffers in console output queue?");
+
+ /* writev can return a partial write, so we loop here. */
+ while (!iov_empty(iov, out)) {
+ int len = writev(STDOUT_FILENO, iov, out);
+ if (len <= 0) {
+ warn("Write to stdout gave %i (%d)", len, errno);
+ break;
+ }
+ iov_consume(vq->dev, iov, out, NULL, len);
+ }
+
+ /*
+ * We're finished with that buffer: if we're going to sleep,
+ * wait_for_vq_desc() will prod the Guest with an interrupt.
+ */
+ add_used(vq, head, 0);
+}
+
+/*
+ * The Network
+ *
+ * Handling output for network is also simple: we get all the output buffers
+ * and write them to /dev/net/tun.
+ */
+struct net_info {
+ int tunfd;
+};
+
+static void net_output(struct virtqueue *vq)
+{
+ struct net_info *net_info = vq->dev->priv;
+ unsigned int head, out, in;
+ struct iovec iov[vq->vring.num];
+
+ /* We usually wait in here for the Guest to give us a packet. */
+ head = wait_for_vq_desc(vq, iov, &out, &in);
+ if (in)
+ bad_driver_vq(vq, "Input buffers in net output queue?");
+ /*
+ * Send the whole thing through to /dev/net/tun. It expects the exact
+ * same format: what a coincidence!
+ */
+ if (writev(net_info->tunfd, iov, out) < 0)
+ warnx("Write to tun failed (%d)?", errno);
+
+ /*
+ * Done with that one; wait_for_vq_desc() will send the interrupt if
+ * all packets are processed.
+ */
+ add_used(vq, head, 0);
+}
+
+/*
+ * Handling network input is a bit trickier, because I've tried to optimize it.
+ *
+ * First we have a helper routine which tells is if from this file descriptor
+ * (ie. the /dev/net/tun device) will block:
+ */
+static bool will_block(int fd)
+{
+ fd_set fdset;
+ struct timeval zero = { 0, 0 };
+ FD_ZERO(&fdset);
+ FD_SET(fd, &fdset);
+ return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
+}
+
+/*
+ * This handles packets coming in from the tun device to our Guest. Like all
+ * service routines, it gets called again as soon as it returns, so you don't
+ * see a while(1) loop here.
+ */
+static void net_input(struct virtqueue *vq)
+{
+ int len;
+ unsigned int head, out, in;
+ struct iovec iov[vq->vring.num];
+ struct net_info *net_info = vq->dev->priv;
+
+ /*
+ * Get a descriptor to write an incoming packet into. This will also
+ * send an interrupt if they're out of descriptors.
+ */
+ head = wait_for_vq_desc(vq, iov, &out, &in);
+ if (out)
+ bad_driver_vq(vq, "Output buffers in net input queue?");
+
+ /*
+ * If it looks like we'll block reading from the tun device, send them
+ * an interrupt.
+ */
+ if (vq->pending_used && will_block(net_info->tunfd))
+ trigger_irq(vq);
+
+ /*
+ * Read in the packet. This is where we normally wait (when there's no
+ * incoming network traffic).
+ */
+ len = readv(net_info->tunfd, iov, in);
+ if (len <= 0)
+ warn("Failed to read from tun (%d).", errno);
+
+ /*
+ * Mark that packet buffer as used, but don't interrupt here. We want
+ * to wait until we've done as much work as we can.
+ */
+ add_used(vq, head, len);
+}
+/*:*/
+
+/* This is the helper to create threads: run the service routine in a loop. */
+static int do_thread(void *_vq)
+{
+ struct virtqueue *vq = _vq;
+
+ for (;;)
+ vq->service(vq);
+ return 0;
+}
+
+/*
+ * When a child dies, we kill our entire process group with SIGTERM. This
+ * also has the side effect that the shell restores the console for us!
+ */
+static void kill_launcher(int signal)
+{
+ kill(0, SIGTERM);
+}
+
+static void reset_vq_pci_config(struct virtqueue *vq)
+{
+ vq->pci_config.queue_size = VIRTQUEUE_NUM;
+ vq->pci_config.queue_enable = 0;
+}
+
+static void reset_device(struct device *dev)
+{
+ struct virtqueue *vq;
+
+ verbose("Resetting device %s\n", dev->name);
+
+ /* Clear any features they've acked. */
+ dev->features_accepted = 0;
+
+ /* We're going to be explicitly killing threads, so ignore them. */
+ signal(SIGCHLD, SIG_IGN);
+
+ /*
+ * 4.1.4.3.1:
+ *
+ * The device MUST present a 0 in queue_enable on reset.
+ *
+ * This means we set it here, and reset the saved ones in every vq.
+ */
+ dev->mmio->cfg.queue_enable = 0;
+
+ /* Get rid of the virtqueue threads */
+ for (vq = dev->vq; vq; vq = vq->next) {
+ vq->last_avail_idx = 0;
+ reset_vq_pci_config(vq);
+ if (vq->thread != (pid_t)-1) {
+ kill(vq->thread, SIGTERM);
+ waitpid(vq->thread, NULL, 0);
+ vq->thread = (pid_t)-1;
+ }
+ }
+ dev->running = false;
+ dev->wrote_features_ok = false;
+
+ /* Now we care if threads die. */
+ signal(SIGCHLD, (void *)kill_launcher);
+}
+
+static void cleanup_devices(void)
+{
+ unsigned int i;
+
+ for (i = 1; i < MAX_PCI_DEVICES; i++) {
+ struct device *d = devices.pci[i];
+ if (!d)
+ continue;
+ reset_device(d);
+ }
+
+ /* If we saved off the original terminal settings, restore them now. */
+ if (orig_term.c_lflag & (ISIG|ICANON|ECHO))
+ tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
+}
+
+/*L:217
+ * We do PCI. This is mainly done to let us test the kernel virtio PCI
+ * code.
+ */
+
+/* Linux expects a PCI host bridge: ours is a dummy, and first on the bus. */
+static struct device pci_host_bridge;
+
+static void init_pci_host_bridge(void)
+{
+ pci_host_bridge.name = "PCI Host Bridge";
+ pci_host_bridge.config.class = 0x06; /* bridge */
+ pci_host_bridge.config.subclass = 0; /* host bridge */
+ devices.pci[0] = &pci_host_bridge;
+}
+
+/* The IO ports used to read the PCI config space. */
+#define PCI_CONFIG_ADDR 0xCF8
+#define PCI_CONFIG_DATA 0xCFC
+
+/*
+ * Not really portable, but does help readability: this is what the Guest
+ * writes to the PCI_CONFIG_ADDR IO port.
+ */
+union pci_config_addr {
+ struct {
+ unsigned mbz: 2;
+ unsigned offset: 6;
+ unsigned funcnum: 3;
+ unsigned devnum: 5;
+ unsigned busnum: 8;
+ unsigned reserved: 7;
+ unsigned enabled : 1;
+ } bits;
+ u32 val;
+};
+
+/*
+ * We cache what they wrote to the address port, so we know what they're
+ * talking about when they access the data port.
+ */
+static union pci_config_addr pci_config_addr;
+
+static struct device *find_pci_device(unsigned int index)
+{
+ return devices.pci[index];
+}
+
+/* PCI can do 1, 2 and 4 byte reads; we handle that here. */
+static void ioread(u16 off, u32 v, u32 mask, u32 *val)
+{
+ assert(off < 4);
+ assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
+ *val = (v >> (off * 8)) & mask;
+}
+
+/* PCI can do 1, 2 and 4 byte writes; we handle that here. */
+static void iowrite(u16 off, u32 v, u32 mask, u32 *dst)
+{
+ assert(off < 4);
+ assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
+ *dst &= ~(mask << (off * 8));
+ *dst |= (v & mask) << (off * 8);
+}
+
+/*
+ * Where PCI_CONFIG_DATA accesses depends on the previous write to
+ * PCI_CONFIG_ADDR.
+ */
+static struct device *dev_and_reg(u32 *reg)
+{
+ if (!pci_config_addr.bits.enabled)
+ return NULL;
+
+ if (pci_config_addr.bits.funcnum != 0)
+ return NULL;
+
+ if (pci_config_addr.bits.busnum != 0)
+ return NULL;
+
+ if (pci_config_addr.bits.offset * 4 >= sizeof(struct pci_config))
+ return NULL;
+
+ *reg = pci_config_addr.bits.offset;
+ return find_pci_device(pci_config_addr.bits.devnum);
+}
+
+/*
+ * We can get invalid combinations of values while they're writing, so we
+ * only fault if they try to write with some invalid bar/offset/length.
+ */
+static bool valid_bar_access(struct device *d,
+ struct virtio_pci_cfg_cap *cfg_access)
+{
+ /* We only have 1 bar (BAR0) */
+ if (cfg_access->cap.bar != 0)
+ return false;
+
+ /* Check it's within BAR0. */
+ if (cfg_access->cap.offset >= d->mmio_size
+ || cfg_access->cap.offset + cfg_access->cap.length > d->mmio_size)
+ return false;
+
+ /* Check length is 1, 2 or 4. */
+ if (cfg_access->cap.length != 1
+ && cfg_access->cap.length != 2
+ && cfg_access->cap.length != 4)
+ return false;
+
+ /*
+ * 4.1.4.7.2:
+ *
+ * The driver MUST NOT write a cap.offset which is not a multiple of
+ * cap.length (ie. all accesses MUST be aligned).
+ */
+ if (cfg_access->cap.offset % cfg_access->cap.length != 0)
+ return false;
+
+ /* Return pointer into word in BAR0. */
+ return true;
+}
+
+/* Is this accessing the PCI config address port?. */
+static bool is_pci_addr_port(u16 port)
+{
+ return port >= PCI_CONFIG_ADDR && port < PCI_CONFIG_ADDR + 4;
+}
+
+static bool pci_addr_iowrite(u16 port, u32 mask, u32 val)
+{
+ iowrite(port - PCI_CONFIG_ADDR, val, mask,
+ &pci_config_addr.val);
+ verbose("PCI%s: %#x/%x: bus %u dev %u func %u reg %u\n",
+ pci_config_addr.bits.enabled ? "" : " DISABLED",
+ val, mask,
+ pci_config_addr.bits.busnum,
+ pci_config_addr.bits.devnum,
+ pci_config_addr.bits.funcnum,
+ pci_config_addr.bits.offset);
+ return true;
+}
+
+static void pci_addr_ioread(u16 port, u32 mask, u32 *val)
+{
+ ioread(port - PCI_CONFIG_ADDR, pci_config_addr.val, mask, val);
+}
+
+/* Is this accessing the PCI config data port?. */
+static bool is_pci_data_port(u16 port)
+{
+ return port >= PCI_CONFIG_DATA && port < PCI_CONFIG_DATA + 4;
+}
+
+static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask);
+
+static bool pci_data_iowrite(u16 port, u32 mask, u32 val)
+{
+ u32 reg, portoff;
+ struct device *d = dev_and_reg(&reg);
+
+ /* Complain if they don't belong to a device. */
+ if (!d)
+ return false;
+
+ /* They can do 1 byte writes, etc. */
+ portoff = port - PCI_CONFIG_DATA;
+
+ /*
+ * PCI uses a weird way to determine the BAR size: the OS
+ * writes all 1's, and sees which ones stick.
+ */
+ if (&d->config_words[reg] == &d->config.bar[0]) {
+ int i;
+
+ iowrite(portoff, val, mask, &d->config.bar[0]);
+ for (i = 0; (1 << i) < d->mmio_size; i++)
+ d->config.bar[0] &= ~(1 << i);
+ return true;
+ } else if ((&d->config_words[reg] > &d->config.bar[0]
+ && &d->config_words[reg] <= &d->config.bar[6])
+ || &d->config_words[reg] == &d->config.expansion_rom_addr) {
+ /* Allow writing to any other BAR, or expansion ROM */
+ iowrite(portoff, val, mask, &d->config_words[reg]);
+ return true;
+ /* We let them overide latency timer and cacheline size */
+ } else if (&d->config_words[reg] == (void *)&d->config.cacheline_size) {
+ /* Only let them change the first two fields. */
+ if (mask == 0xFFFFFFFF)
+ mask = 0xFFFF;
+ iowrite(portoff, val, mask, &d->config_words[reg]);
+ return true;
+ } else if (&d->config_words[reg] == (void *)&d->config.command
+ && mask == 0xFFFF) {
+ /* Ignore command writes. */
+ return true;
+ } else if (&d->config_words[reg]
+ == (void *)&d->config.cfg_access.cap.bar
+ || &d->config_words[reg]
+ == &d->config.cfg_access.cap.length
+ || &d->config_words[reg]
+ == &d->config.cfg_access.cap.offset) {
+
+ /*
+ * The VIRTIO_PCI_CAP_PCI_CFG capability
+ * provides a backdoor to access the MMIO
+ * regions without mapping them. Weird, but
+ * useful.
+ */
+ iowrite(portoff, val, mask, &d->config_words[reg]);
+ return true;
+ } else if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
+ u32 write_mask;
+
+ /*
+ * 4.1.4.7.1:
+ *
+ * Upon detecting driver write access to pci_cfg_data, the
+ * device MUST execute a write access at offset cap.offset at
+ * BAR selected by cap.bar using the first cap.length bytes
+ * from pci_cfg_data.
+ */
+
+ /* Must be bar 0 */
+ if (!valid_bar_access(d, &d->config.cfg_access))
+ return false;
+
+ iowrite(portoff, val, mask, &d->config.cfg_access.pci_cfg_data);
+
+ /*
+ * Now emulate a write. The mask we use is set by
+ * len, *not* this write!
+ */
+ write_mask = (1ULL<<(8*d->config.cfg_access.cap.length)) - 1;
+ verbose("Window writing %#x/%#x to bar %u, offset %u len %u\n",
+ d->config.cfg_access.pci_cfg_data, write_mask,
+ d->config.cfg_access.cap.bar,
+ d->config.cfg_access.cap.offset,
+ d->config.cfg_access.cap.length);
+
+ emulate_mmio_write(d, d->config.cfg_access.cap.offset,
+ d->config.cfg_access.pci_cfg_data,
+ write_mask);
+ return true;
+ }
+
+ /*
+ * 4.1.4.1:
+ *
+ * The driver MUST NOT write into any field of the capability
+ * structure, with the exception of those with cap_type
+ * VIRTIO_PCI_CAP_PCI_CFG...
+ */
+ return false;
+}
+
+static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask);
+
+static void pci_data_ioread(u16 port, u32 mask, u32 *val)
+{
+ u32 reg;
+ struct device *d = dev_and_reg(&reg);
+
+ if (!d)
+ return;
+
+ /* Read through the PCI MMIO access window is special */
+ if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
+ u32 read_mask;
+
+ /*
+ * 4.1.4.7.1:
+ *
+ * Upon detecting driver read access to pci_cfg_data, the
+ * device MUST execute a read access of length cap.length at
+ * offset cap.offset at BAR selected by cap.bar and store the
+ * first cap.length bytes in pci_cfg_data.
+ */
+ /* Must be bar 0 */
+ if (!valid_bar_access(d, &d->config.cfg_access))
+ bad_driver(d,
+ "Invalid cfg_access to bar%u, offset %u len %u",
+ d->config.cfg_access.cap.bar,
+ d->config.cfg_access.cap.offset,
+ d->config.cfg_access.cap.length);
+
+ /*
+ * Read into the window. The mask we use is set by
+ * len, *not* this read!
+ */
+ read_mask = (1ULL<<(8*d->config.cfg_access.cap.length))-1;
+ d->config.cfg_access.pci_cfg_data
+ = emulate_mmio_read(d,
+ d->config.cfg_access.cap.offset,
+ read_mask);
+ verbose("Window read %#x/%#x from bar %u, offset %u len %u\n",
+ d->config.cfg_access.pci_cfg_data, read_mask,
+ d->config.cfg_access.cap.bar,
+ d->config.cfg_access.cap.offset,
+ d->config.cfg_access.cap.length);
+ }
+ ioread(port - PCI_CONFIG_DATA, d->config_words[reg], mask, val);
+}
+
+/*L:216
+ * This is where we emulate a handful of Guest instructions. It's ugly
+ * and we used to do it in the kernel but it grew over time.
+ */
+
+/*
+ * We use the ptrace syscall's pt_regs struct to talk about registers
+ * to lguest: these macros convert the names to the offsets.
+ */
+#define getreg(name) getreg_off(offsetof(struct user_regs_struct, name))
+#define setreg(name, val) \
+ setreg_off(offsetof(struct user_regs_struct, name), (val))
+
+static u32 getreg_off(size_t offset)
+{
+ u32 r;
+ unsigned long args[] = { LHREQ_GETREG, offset };
+
+ if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
+ err(1, "Getting register %u", offset);
+ if (pread(lguest_fd, &r, sizeof(r), cpu_id) != sizeof(r))
+ err(1, "Reading register %u", offset);
+
+ return r;
+}
+
+static void setreg_off(size_t offset, u32 val)
+{
+ unsigned long args[] = { LHREQ_SETREG, offset, val };
+
+ if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
+ err(1, "Setting register %u", offset);
+}
+
+/* Get register by instruction encoding */
+static u32 getreg_num(unsigned regnum, u32 mask)
+{
+ /* 8 bit ops use regnums 4-7 for high parts of word */
+ if (mask == 0xFF && (regnum & 0x4))
+ return getreg_num(regnum & 0x3, 0xFFFF) >> 8;
+
+ switch (regnum) {
+ case 0: return getreg(eax) & mask;
+ case 1: return getreg(ecx) & mask;
+ case 2: return getreg(edx) & mask;
+ case 3: return getreg(ebx) & mask;
+ case 4: return getreg(esp) & mask;
+ case 5: return getreg(ebp) & mask;
+ case 6: return getreg(esi) & mask;
+ case 7: return getreg(edi) & mask;
+ }
+ abort();
+}
+
+/* Set register by instruction encoding */
+static void setreg_num(unsigned regnum, u32 val, u32 mask)
+{
+ /* Don't try to set bits out of range */
+ assert(~(val & ~mask));
+
+ /* 8 bit ops use regnums 4-7 for high parts of word */
+ if (mask == 0xFF && (regnum & 0x4)) {
+ /* Construct the 16 bits we want. */
+ val = (val << 8) | getreg_num(regnum & 0x3, 0xFF);
+ setreg_num(regnum & 0x3, val, 0xFFFF);
+ return;
+ }
+
+ switch (regnum) {
+ case 0: setreg(eax, val | (getreg(eax) & ~mask)); return;
+ case 1: setreg(ecx, val | (getreg(ecx) & ~mask)); return;
+ case 2: setreg(edx, val | (getreg(edx) & ~mask)); return;
+ case 3: setreg(ebx, val | (getreg(ebx) & ~mask)); return;
+ case 4: setreg(esp, val | (getreg(esp) & ~mask)); return;
+ case 5: setreg(ebp, val | (getreg(ebp) & ~mask)); return;
+ case 6: setreg(esi, val | (getreg(esi) & ~mask)); return;
+ case 7: setreg(edi, val | (getreg(edi) & ~mask)); return;
+ }
+ abort();
+}
+
+/* Get bytes of displacement appended to instruction, from r/m encoding */
+static u32 insn_displacement_len(u8 mod_reg_rm)
+{
+ /* Switch on the mod bits */
+ switch (mod_reg_rm >> 6) {
+ case 0:
+ /* If mod == 0, and r/m == 101, 16-bit displacement follows */
+ if ((mod_reg_rm & 0x7) == 0x5)
+ return 2;
+ /* Normally, mod == 0 means no literal displacement */
+ return 0;
+ case 1:
+ /* One byte displacement */
+ return 1;
+ case 2:
+ /* Four byte displacement */
+ return 4;
+ case 3:
+ /* Register mode */
+ return 0;
+ }
+ abort();
+}
+
+static void emulate_insn(const u8 insn[])
+{
+ unsigned long args[] = { LHREQ_TRAP, 13 };
+ unsigned int insnlen = 0, in = 0, small_operand = 0, byte_access;
+ unsigned int eax, port, mask;
+ /*
+ * Default is to return all-ones on IO port reads, which traditionally
+ * means "there's nothing there".
+ */
+ u32 val = 0xFFFFFFFF;
+
+ /*
+ * This must be the Guest kernel trying to do something, not userspace!
+ * The bottom two bits of the CS segment register are the privilege
+ * level.
+ */
+ if ((getreg(xcs) & 3) != 0x1)
+ goto no_emulate;
+
+ /* Decoding x86 instructions is icky. */
+
+ /*
+ * Around 2.6.33, the kernel started using an emulation for the
+ * cmpxchg8b instruction in early boot on many configurations. This
+ * code isn't paravirtualized, and it tries to disable interrupts.
+ * Ignore it, which will Mostly Work.
+ */
+ if (insn[insnlen] == 0xfa) {
+ /* "cli", or Clear Interrupt Enable instruction. Skip it. */
+ insnlen = 1;
+ goto skip_insn;
+ }
+
+ /*
+ * 0x66 is an "operand prefix". It means a 16, not 32 bit in/out.
+ */
+ if (insn[insnlen] == 0x66) {
+ small_operand = 1;
+ /* The instruction is 1 byte so far, read the next byte. */
+ insnlen = 1;
+ }
+
+ /* If the lower bit isn't set, it's a single byte access */
+ byte_access = !(insn[insnlen] & 1);
+
+ /*
+ * Now we can ignore the lower bit and decode the 4 opcodes
+ * we need to emulate.
+ */
+ switch (insn[insnlen] & 0xFE) {
+ case 0xE4: /* in <next byte>,%al */
+ port = insn[insnlen+1];
+ insnlen += 2;
+ in = 1;
+ break;
+ case 0xEC: /* in (%dx),%al */
+ port = getreg(edx) & 0xFFFF;
+ insnlen += 1;
+ in = 1;
+ break;
+ case 0xE6: /* out %al,<next byte> */
+ port = insn[insnlen+1];
+ insnlen += 2;
+ break;
+ case 0xEE: /* out %al,(%dx) */
+ port = getreg(edx) & 0xFFFF;
+ insnlen += 1;
+ break;
+ default:
+ /* OK, we don't know what this is, can't emulate. */
+ goto no_emulate;
+ }
+
+ /* Set a mask of the 1, 2 or 4 bytes, depending on size of IO */
+ if (byte_access)
+ mask = 0xFF;
+ else if (small_operand)
+ mask = 0xFFFF;
+ else
+ mask = 0xFFFFFFFF;
+
+ /*
+ * If it was an "IN" instruction, they expect the result to be read
+ * into %eax, so we change %eax.
+ */
+ eax = getreg(eax);
+
+ if (in) {
+ /* This is the PS/2 keyboard status; 1 means ready for output */
+ if (port == 0x64)
+ val = 1;
+ else if (is_pci_addr_port(port))
+ pci_addr_ioread(port, mask, &val);
+ else if (is_pci_data_port(port))
+ pci_data_ioread(port, mask, &val);
+
+ /* Clear the bits we're about to read */
+ eax &= ~mask;
+ /* Copy bits in from val. */
+ eax |= val & mask;
+ /* Now update the register. */
+ setreg(eax, eax);
+ } else {
+ if (is_pci_addr_port(port)) {
+ if (!pci_addr_iowrite(port, mask, eax))
+ goto bad_io;
+ } else if (is_pci_data_port(port)) {
+ if (!pci_data_iowrite(port, mask, eax))
+ goto bad_io;
+ }
+ /* There are many other ports, eg. CMOS clock, serial
+ * and parallel ports, so we ignore them all. */
+ }
+
+ verbose("IO %s of %x to %u: %#08x\n",
+ in ? "IN" : "OUT", mask, port, eax);
+skip_insn:
+ /* Finally, we've "done" the instruction, so move past it. */
+ setreg(eip, getreg(eip) + insnlen);
+ return;
+
+bad_io:
+ warnx("Attempt to %s port %u (%#x mask)",
+ in ? "read from" : "write to", port, mask);
+
+no_emulate:
+ /* Inject trap into Guest. */
+ if (write(lguest_fd, args, sizeof(args)) < 0)
+ err(1, "Reinjecting trap 13 for fault at %#x", getreg(eip));
+}
+
+static struct device *find_mmio_region(unsigned long paddr, u32 *off)
+{
+ unsigned int i;
+
+ for (i = 1; i < MAX_PCI_DEVICES; i++) {
+ struct device *d = devices.pci[i];
+
+ if (!d)
+ continue;
+ if (paddr < d->mmio_addr)
+ continue;
+ if (paddr >= d->mmio_addr + d->mmio_size)
+ continue;
+ *off = paddr - d->mmio_addr;
+ return d;
+ }
+ return NULL;
+}
+
+/* FIXME: Use vq array. */
+static struct virtqueue *vq_by_num(struct device *d, u32 num)
+{
+ struct virtqueue *vq = d->vq;
+
+ while (num-- && vq)
+ vq = vq->next;
+
+ return vq;
+}
+
+static void save_vq_config(const struct virtio_pci_common_cfg *cfg,
+ struct virtqueue *vq)
+{
+ vq->pci_config = *cfg;
+}
+
+static void restore_vq_config(struct virtio_pci_common_cfg *cfg,
+ struct virtqueue *vq)
+{
+ /* Only restore the per-vq part */
+ size_t off = offsetof(struct virtio_pci_common_cfg, queue_size);
+
+ memcpy((void *)cfg + off, (void *)&vq->pci_config + off,
+ sizeof(*cfg) - off);
+}
+
+/*
+ * 4.1.4.3.2:
+ *
+ * The driver MUST configure the other virtqueue fields before
+ * enabling the virtqueue with queue_enable.
+ *
+ * When they enable the virtqueue, we check that their setup is valid.
+ */
+static void check_virtqueue(struct device *d, struct virtqueue *vq)
+{
+ /* Because lguest is 32 bit, all the descriptor high bits must be 0 */
+ if (vq->pci_config.queue_desc_hi
+ || vq->pci_config.queue_avail_hi
+ || vq->pci_config.queue_used_hi)
+ bad_driver_vq(vq, "invalid 64-bit queue address");
+
+ /*
+ * 2.4.1:
+ *
+ * The driver MUST ensure that the physical address of the first byte
+ * of each virtqueue part is a multiple of the specified alignment
+ * value in the above table.
+ */
+ if (vq->pci_config.queue_desc_lo % 16
+ || vq->pci_config.queue_avail_lo % 2
+ || vq->pci_config.queue_used_lo % 4)
+ bad_driver_vq(vq, "invalid alignment in queue addresses");
+
+ /* Initialize the virtqueue and check they're all in range. */
+ vq->vring.num = vq->pci_config.queue_size;
+ vq->vring.desc = check_pointer(vq->dev,
+ vq->pci_config.queue_desc_lo,
+ sizeof(*vq->vring.desc) * vq->vring.num);
+ vq->vring.avail = check_pointer(vq->dev,
+ vq->pci_config.queue_avail_lo,
+ sizeof(*vq->vring.avail)
+ + (sizeof(vq->vring.avail->ring[0])
+ * vq->vring.num));
+ vq->vring.used = check_pointer(vq->dev,
+ vq->pci_config.queue_used_lo,
+ sizeof(*vq->vring.used)
+ + (sizeof(vq->vring.used->ring[0])
+ * vq->vring.num));
+
+ /*
+ * 2.4.9.1:
+ *
+ * The driver MUST initialize flags in the used ring to 0
+ * when allocating the used ring.
+ */
+ if (vq->vring.used->flags != 0)
+ bad_driver_vq(vq, "invalid initial used.flags %#x",
+ vq->vring.used->flags);
+}
+
+static void start_virtqueue(struct virtqueue *vq)
+{
+ /*
+ * Create stack for thread. Since the stack grows upwards, we point
+ * the stack pointer to the end of this region.
+ */
+ char *stack = malloc(32768);
+
+ /* Create a zero-initialized eventfd. */
+ vq->eventfd = eventfd(0, 0);
+ if (vq->eventfd < 0)
+ err(1, "Creating eventfd");
+
+ /*
+ * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so
+ * we get a signal if it dies.
+ */
+ vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq);
+ if (vq->thread == (pid_t)-1)
+ err(1, "Creating clone");
+}
+
+static void start_virtqueues(struct device *d)
+{
+ struct virtqueue *vq;
+
+ for (vq = d->vq; vq; vq = vq->next) {
+ if (vq->pci_config.queue_enable)
+ start_virtqueue(vq);
+ }
+}
+
+static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
+{
+ struct virtqueue *vq;
+
+ switch (off) {
+ case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
+ /*
+ * 4.1.4.3.1:
+ *
+ * The device MUST present the feature bits it is offering in
+ * device_feature, starting at bit device_feature_select ∗ 32
+ * for any device_feature_select written by the driver
+ */
+ if (val == 0)
+ d->mmio->cfg.device_feature = d->features;
+ else if (val == 1)
+ d->mmio->cfg.device_feature = (d->features >> 32);
+ else
+ d->mmio->cfg.device_feature = 0;
+ goto feature_write_through32;
+ case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
+ if (val > 1)
+ bad_driver(d, "Unexpected driver select %u", val);
+ goto feature_write_through32;
+ case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
+ if (d->mmio->cfg.guest_feature_select == 0) {
+ d->features_accepted &= ~((u64)0xFFFFFFFF);
+ d->features_accepted |= val;
+ } else {
+ assert(d->mmio->cfg.guest_feature_select == 1);
+ d->features_accepted &= 0xFFFFFFFF;
+ d->features_accepted |= ((u64)val) << 32;
+ }
+ /*
+ * 2.2.1:
+ *
+ * The driver MUST NOT accept a feature which the device did
+ * not offer
+ */
+ if (d->features_accepted & ~d->features)
+ bad_driver(d, "over-accepted features %#llx of %#llx",
+ d->features_accepted, d->features);
+ goto feature_write_through32;
+ case offsetof(struct virtio_pci_mmio, cfg.device_status): {
+ u8 prev;
+
+ verbose("%s: device status -> %#x\n", d->name, val);
+ /*
+ * 4.1.4.3.1:
+ *
+ * The device MUST reset when 0 is written to device_status,
+ * and present a 0 in device_status once that is done.
+ */
+ if (val == 0) {
+ reset_device(d);
+ goto write_through8;
+ }
+
+ /* 2.1.1: The driver MUST NOT clear a device status bit. */
+ if (d->mmio->cfg.device_status & ~val)
+ bad_driver(d, "unset of device status bit %#x -> %#x",
+ d->mmio->cfg.device_status, val);
+
+ /*
+ * 2.1.2:
+ *
+ * The device MUST NOT consume buffers or notify the driver
+ * before DRIVER_OK.
+ */
+ if (val & VIRTIO_CONFIG_S_DRIVER_OK
+ && !(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
+ start_virtqueues(d);
+
+ /*
+ * 3.1.1:
+ *
+ * The driver MUST follow this sequence to initialize a device:
+ * - Reset the device.
+ * - Set the ACKNOWLEDGE status bit: the guest OS has
+ * notice the device.
+ * - Set the DRIVER status bit: the guest OS knows how
+ * to drive the device.
+ * - Read device feature bits, and write the subset
+ * of feature bits understood by the OS and driver
+ * to the device. During this step the driver MAY
+ * read (but MUST NOT write) the device-specific
+ * configuration fields to check that it can
+ * support the device before accepting it.
+ * - Set the FEATURES_OK status bit. The driver
+ * MUST not accept new feature bits after this
+ * step.
+ * - Re-read device status to ensure the FEATURES_OK
+ * bit is still set: otherwise, the device does
+ * not support our subset of features and the
+ * device is unusable.
+ * - Perform device-specific setup, including
+ * discovery of virtqueues for the device,
+ * optional per-bus setup, reading and possibly
+ * writing the device’s virtio configuration
+ * space, and population of virtqueues.
+ * - Set the DRIVER_OK status bit. At this point the
+ * device is “live”.
+ */
+ prev = 0;
+ switch (val & ~d->mmio->cfg.device_status) {
+ case VIRTIO_CONFIG_S_DRIVER_OK:
+ prev |= VIRTIO_CONFIG_S_FEATURES_OK; /* fall thru */
+ case VIRTIO_CONFIG_S_FEATURES_OK:
+ prev |= VIRTIO_CONFIG_S_DRIVER; /* fall thru */
+ case VIRTIO_CONFIG_S_DRIVER:
+ prev |= VIRTIO_CONFIG_S_ACKNOWLEDGE; /* fall thru */
+ case VIRTIO_CONFIG_S_ACKNOWLEDGE:
+ break;
+ default:
+ bad_driver(d, "unknown device status bit %#x -> %#x",
+ d->mmio->cfg.device_status, val);
+ }
+ if (d->mmio->cfg.device_status != prev)
+ bad_driver(d, "unexpected status transition %#x -> %#x",
+ d->mmio->cfg.device_status, val);
+
+ /* If they just wrote FEATURES_OK, we make sure they read */
+ switch (val & ~d->mmio->cfg.device_status) {
+ case VIRTIO_CONFIG_S_FEATURES_OK:
+ d->wrote_features_ok = true;
+ break;
+ case VIRTIO_CONFIG_S_DRIVER_OK:
+ if (d->wrote_features_ok)
+ bad_driver(d, "did not re-read FEATURES_OK");
+ break;
+ }
+ goto write_through8;
+ }
+ case offsetof(struct virtio_pci_mmio, cfg.queue_select):
+ vq = vq_by_num(d, val);
+ /*
+ * 4.1.4.3.1:
+ *
+ * The device MUST present a 0 in queue_size if the virtqueue
+ * corresponding to the current queue_select is unavailable.
+ */
+ if (!vq) {
+ d->mmio->cfg.queue_size = 0;
+ goto write_through16;
+ }
+ /* Save registers for old vq, if it was a valid vq */
+ if (d->mmio->cfg.queue_size)
+ save_vq_config(&d->mmio->cfg,
+ vq_by_num(d, d->mmio->cfg.queue_select));
+ /* Restore the registers for the queue they asked for */
+ restore_vq_config(&d->mmio->cfg, vq);
+ goto write_through16;
+ case offsetof(struct virtio_pci_mmio, cfg.queue_size):
+ /*
+ * 4.1.4.3.2:
+ *
+ * The driver MUST NOT write a value which is not a power of 2
+ * to queue_size.
+ */
+ if (val & (val-1))
+ bad_driver(d, "invalid queue size %u", val);
+ if (d->mmio->cfg.queue_enable)
+ bad_driver(d, "changing queue size on live device");
+ goto write_through16;
+ case offsetof(struct virtio_pci_mmio, cfg.queue_msix_vector):
+ bad_driver(d, "attempt to set MSIX vector to %u", val);
+ case offsetof(struct virtio_pci_mmio, cfg.queue_enable): {
+ struct virtqueue *vq = vq_by_num(d, d->mmio->cfg.queue_select);
+
+ /*
+ * 4.1.4.3.2:
+ *
+ * The driver MUST NOT write a 0 to queue_enable.
+ */
+ if (val != 1)
+ bad_driver(d, "setting queue_enable to %u", val);
+
+ /*
+ * 3.1.1:
+ *
+ * 7. Perform device-specific setup, including discovery of
+ * virtqueues for the device, optional per-bus setup,
+ * reading and possibly writing the device’s virtio
+ * configuration space, and population of virtqueues.
+ * 8. Set the DRIVER_OK status bit.
+ *
+ * All our devices require all virtqueues to be enabled, so
+ * they should have done that before setting DRIVER_OK.
+ */
+ if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)
+ bad_driver(d, "enabling vq after DRIVER_OK");
+
+ d->mmio->cfg.queue_enable = val;
+ save_vq_config(&d->mmio->cfg, vq);
+ check_virtqueue(d, vq);
+ goto write_through16;
+ }
+ case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off):
+ bad_driver(d, "attempt to write to queue_notify_off");
+ case offsetof(struct virtio_pci_mmio, cfg.queue_desc_lo):
+ case offsetof(struct virtio_pci_mmio, cfg.queue_desc_hi):
+ case offsetof(struct virtio_pci_mmio, cfg.queue_avail_lo):
+ case offsetof(struct virtio_pci_mmio, cfg.queue_avail_hi):
+ case offsetof(struct virtio_pci_mmio, cfg.queue_used_lo):
+ case offsetof(struct virtio_pci_mmio, cfg.queue_used_hi):
+ /*
+ * 4.1.4.3.2:
+ *
+ * The driver MUST configure the other virtqueue fields before
+ * enabling the virtqueue with queue_enable.
+ */
+ if (d->mmio->cfg.queue_enable)
+ bad_driver(d, "changing queue on live device");
+
+ /*
+ * 3.1.1:
+ *
+ * The driver MUST follow this sequence to initialize a device:
+ *...
+ * 5. Set the FEATURES_OK status bit. The driver MUST not
+ * accept new feature bits after this step.
+ */
+ if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK))
+ bad_driver(d, "setting up vq before FEATURES_OK");
+
+ /*
+ * 6. Re-read device status to ensure the FEATURES_OK bit is
+ * still set...
+ */
+ if (d->wrote_features_ok)
+ bad_driver(d, "didn't re-read FEATURES_OK before setup");
+
+ goto write_through32;
+ case offsetof(struct virtio_pci_mmio, notify):
+ vq = vq_by_num(d, val);
+ if (!vq)
+ bad_driver(d, "Invalid vq notification on %u", val);
+ /* Notify the process handling this vq by adding 1 to eventfd */
+ write(vq->eventfd, "\1\0\0\0\0\0\0\0", 8);
+ goto write_through16;
+ case offsetof(struct virtio_pci_mmio, isr):
+ bad_driver(d, "Unexpected write to isr");
+ /* Weird corner case: write to emerg_wr of console */
+ case sizeof(struct virtio_pci_mmio)
+ + offsetof(struct virtio_console_config, emerg_wr):
+ if (strcmp(d->name, "console") == 0) {
+ char c = val;
+ write(STDOUT_FILENO, &c, 1);
+ goto write_through32;
+ }
+ /* Fall through... */
+ default:
+ /*
+ * 4.1.4.3.2:
+ *
+ * The driver MUST NOT write to device_feature, num_queues,
+ * config_generation or queue_notify_off.
+ */
+ bad_driver(d, "Unexpected write to offset %u", off);
+ }
+
+feature_write_through32:
+ /*
+ * 3.1.1:
+ *
+ * The driver MUST follow this sequence to initialize a device:
+ *...
+ * - Set the DRIVER status bit: the guest OS knows how
+ * to drive the device.
+ * - Read device feature bits, and write the subset
+ * of feature bits understood by the OS and driver
+ * to the device.
+ *...
+ * - Set the FEATURES_OK status bit. The driver MUST not
+ * accept new feature bits after this step.
+ */
+ if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
+ bad_driver(d, "feature write before VIRTIO_CONFIG_S_DRIVER");
+ if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK)
+ bad_driver(d, "feature write after VIRTIO_CONFIG_S_FEATURES_OK");
+
+ /*
+ * 4.1.3.1:
+ *
+ * The driver MUST access each field using the “natural” access
+ * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
+ * 16-bit fields and 8-bit accesses for 8-bit fields.
+ */
+write_through32:
+ if (mask != 0xFFFFFFFF) {
+ bad_driver(d, "non-32-bit write to offset %u (%#x)",
+ off, getreg(eip));
+ return;
+ }
+ memcpy((char *)d->mmio + off, &val, 4);
+ return;
+
+write_through16:
+ if (mask != 0xFFFF)
+ bad_driver(d, "non-16-bit write to offset %u (%#x)",
+ off, getreg(eip));
+ memcpy((char *)d->mmio + off, &val, 2);
+ return;
+
+write_through8:
+ if (mask != 0xFF)
+ bad_driver(d, "non-8-bit write to offset %u (%#x)",
+ off, getreg(eip));
+ memcpy((char *)d->mmio + off, &val, 1);
+ return;
+}
+
+static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
+{
+ u8 isr;
+ u32 val = 0;
+
+ switch (off) {
+ case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
+ case offsetof(struct virtio_pci_mmio, cfg.device_feature):
+ case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
+ case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
+ /*
+ * 3.1.1:
+ *
+ * The driver MUST follow this sequence to initialize a device:
+ *...
+ * - Set the DRIVER status bit: the guest OS knows how
+ * to drive the device.
+ * - Read device feature bits, and write the subset
+ * of feature bits understood by the OS and driver
+ * to the device.
+ */
+ if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
+ bad_driver(d,
+ "feature read before VIRTIO_CONFIG_S_DRIVER");
+ goto read_through32;
+ case offsetof(struct virtio_pci_mmio, cfg.msix_config):
+ bad_driver(d, "read of msix_config");
+ case offsetof(struct virtio_pci_mmio, cfg.num_queues):
+ goto read_through16;
+ case offsetof(struct virtio_pci_mmio, cfg.device_status):
+ /* As they did read, any write of FEATURES_OK is now fine. */
+ d->wrote_features_ok = false;
+ goto read_through8;
+ case offsetof(struct virtio_pci_mmio, cfg.config_generation):
+ /*
+ * 4.1.4.3.1:
+ *
+ * The device MUST present a changed config_generation after
+ * the driver has read a device-specific configuration value
+ * which has changed since any part of the device-specific
+ * configuration was last read.
+ *
+ * This is simple: none of our devices change config, so this
+ * is always 0.
+ */
+ goto read_through8;
+ case offsetof(struct virtio_pci_mmio, notify):
+ /*
+ * 3.1.1:
+ *
+ * The driver MUST NOT notify the device before setting
+ * DRIVER_OK.
+ */
+ if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
+ bad_driver(d, "notify before VIRTIO_CONFIG_S_DRIVER_OK");
+ goto read_through16;
+ case offsetof(struct virtio_pci_mmio, isr):
+ if (mask != 0xFF)
+ bad_driver(d, "non-8-bit read from offset %u (%#x)",
+ off, getreg(eip));
+ isr = d->mmio->isr;
+ /*
+ * 4.1.4.5.1:
+ *
+ * The device MUST reset ISR status to 0 on driver read.
+ */
+ d->mmio->isr = 0;
+ return isr;
+ case offsetof(struct virtio_pci_mmio, padding):
+ bad_driver(d, "read from padding (%#x)", getreg(eip));
+ default:
+ /* Read from device config space, beware unaligned overflow */
+ if (off > d->mmio_size - 4)
+ bad_driver(d, "read past end (%#x)", getreg(eip));
+
+ /*
+ * 3.1.1:
+ * The driver MUST follow this sequence to initialize a device:
+ *...
+ * 3. Set the DRIVER status bit: the guest OS knows how to
+ * drive the device.
+ * 4. Read device feature bits, and write the subset of
+ * feature bits understood by the OS and driver to the
+ * device. During this step the driver MAY read (but MUST NOT
+ * write) the device-specific configuration fields to check
+ * that it can support the device before accepting it.
+ */
+ if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
+ bad_driver(d,
+ "config read before VIRTIO_CONFIG_S_DRIVER");
+
+ if (mask == 0xFFFFFFFF)
+ goto read_through32;
+ else if (mask == 0xFFFF)
+ goto read_through16;
+ else
+ goto read_through8;
+ }
+
+ /*
+ * 4.1.3.1:
+ *
+ * The driver MUST access each field using the “natural” access
+ * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
+ * 16-bit fields and 8-bit accesses for 8-bit fields.
+ */
+read_through32:
+ if (mask != 0xFFFFFFFF)
+ bad_driver(d, "non-32-bit read to offset %u (%#x)",
+ off, getreg(eip));
+ memcpy(&val, (char *)d->mmio + off, 4);
+ return val;
+
+read_through16:
+ if (mask != 0xFFFF)
+ bad_driver(d, "non-16-bit read to offset %u (%#x)",
+ off, getreg(eip));
+ memcpy(&val, (char *)d->mmio + off, 2);
+ return val;
+
+read_through8:
+ if (mask != 0xFF)
+ bad_driver(d, "non-8-bit read to offset %u (%#x)",
+ off, getreg(eip));
+ memcpy(&val, (char *)d->mmio + off, 1);
+ return val;
+}
+
+static void emulate_mmio(unsigned long paddr, const u8 *insn)
+{
+ u32 val, off, mask = 0xFFFFFFFF, insnlen = 0;
+ struct device *d = find_mmio_region(paddr, &off);
+ unsigned long args[] = { LHREQ_TRAP, 14 };
+
+ if (!d) {
+ warnx("MMIO touching %#08lx (not a device)", paddr);
+ goto reinject;
+ }
+
+ /* Prefix makes it a 16 bit op */
+ if (insn[0] == 0x66) {
+ mask = 0xFFFF;
+ insnlen++;
+ }
+
+ /* iowrite */
+ if (insn[insnlen] == 0x89) {
+ /* Next byte is r/m byte: bits 3-5 are register. */
+ val = getreg_num((insn[insnlen+1] >> 3) & 0x7, mask);
+ emulate_mmio_write(d, off, val, mask);
+ insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
+ } else if (insn[insnlen] == 0x8b) { /* ioread */
+ /* Next byte is r/m byte: bits 3-5 are register. */
+ val = emulate_mmio_read(d, off, mask);
+ setreg_num((insn[insnlen+1] >> 3) & 0x7, val, mask);
+ insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
+ } else if (insn[0] == 0x88) { /* 8-bit iowrite */
+ mask = 0xff;
+ /* Next byte is r/m byte: bits 3-5 are register. */
+ val = getreg_num((insn[1] >> 3) & 0x7, mask);
+ emulate_mmio_write(d, off, val, mask);
+ insnlen = 2 + insn_displacement_len(insn[1]);
+ } else if (insn[0] == 0x8a) { /* 8-bit ioread */
+ mask = 0xff;
+ val = emulate_mmio_read(d, off, mask);
+ setreg_num((insn[1] >> 3) & 0x7, val, mask);
+ insnlen = 2 + insn_displacement_len(insn[1]);
+ } else {
+ warnx("Unknown MMIO instruction touching %#08lx:"
+ " %02x %02x %02x %02x at %u",
+ paddr, insn[0], insn[1], insn[2], insn[3], getreg(eip));
+ reinject:
+ /* Inject trap into Guest. */
+ if (write(lguest_fd, args, sizeof(args)) < 0)
+ err(1, "Reinjecting trap 14 for fault at %#x",
+ getreg(eip));
+ return;
+ }
+
+ /* Finally, we've "done" the instruction, so move past it. */
+ setreg(eip, getreg(eip) + insnlen);
+}
+
+/*L:190
+ * Device Setup
+ *
+ * All devices need a descriptor so the Guest knows it exists, and a "struct
+ * device" so the Launcher can keep track of it. We have common helper
+ * routines to allocate and manage them.
+ */
+static void add_pci_virtqueue(struct device *dev,
+ void (*service)(struct virtqueue *),
+ const char *name)
+{
+ struct virtqueue **i, *vq = malloc(sizeof(*vq));
+
+ /* Initialize the virtqueue */
+ vq->next = NULL;
+ vq->last_avail_idx = 0;
+ vq->dev = dev;
+ vq->name = name;
+
+ /*
+ * This is the routine the service thread will run, and its Process ID
+ * once it's running.
+ */
+ vq->service = service;
+ vq->thread = (pid_t)-1;
+
+ /* Initialize the configuration. */
+ reset_vq_pci_config(vq);
+ vq->pci_config.queue_notify_off = 0;
+
+ /* Add one to the number of queues */
+ vq->dev->mmio->cfg.num_queues++;
+
+ /*
+ * Add to tail of list, so dev->vq is first vq, dev->vq->next is
+ * second.
+ */
+ for (i = &dev->vq; *i; i = &(*i)->next);
+ *i = vq;
+}
+
+/* The Guest accesses the feature bits via the PCI common config MMIO region */
+static void add_pci_feature(struct device *dev, unsigned bit)
+{
+ dev->features |= (1ULL << bit);
+}
+
+/* For devices with no config. */
+static void no_device_config(struct device *dev)
+{
+ dev->mmio_addr = get_mmio_region(dev->mmio_size);
+
+ dev->config.bar[0] = dev->mmio_addr;
+ /* Bottom 4 bits must be zero */
+ assert(~(dev->config.bar[0] & 0xF));
+}
+
+/* This puts the device config into BAR0 */
+static void set_device_config(struct device *dev, const void *conf, size_t len)
+{
+ /* Set up BAR 0 */
+ dev->mmio_size += len;
+ dev->mmio = realloc(dev->mmio, dev->mmio_size);
+ memcpy(dev->mmio + 1, conf, len);
+
+ /*
+ * 4.1.4.6:
+ *
+ * The device MUST present at least one VIRTIO_PCI_CAP_DEVICE_CFG
+ * capability for any device type which has a device-specific
+ * configuration.
+ */
+ /* Hook up device cfg */
+ dev->config.cfg_access.cap.cap_next
+ = offsetof(struct pci_config, device);
+
+ /*
+ * 4.1.4.6.1:
+ *
+ * The offset for the device-specific configuration MUST be 4-byte
+ * aligned.
+ */
+ assert(dev->config.cfg_access.cap.cap_next % 4 == 0);
+
+ /* Fix up device cfg field length. */
+ dev->config.device.length = len;
+
+ /* The rest is the same as the no-config case */
+ no_device_config(dev);
+}
+
+static void init_cap(struct virtio_pci_cap *cap, size_t caplen, int type,
+ size_t bar_offset, size_t bar_bytes, u8 next)
+{
+ cap->cap_vndr = PCI_CAP_ID_VNDR;
+ cap->cap_next = next;
+ cap->cap_len = caplen;
+ cap->cfg_type = type;
+ cap->bar = 0;
+ memset(cap->padding, 0, sizeof(cap->padding));
+ cap->offset = bar_offset;
+ cap->length = bar_bytes;
+}
+
+/*
+ * This sets up the pci_config structure, as defined in the virtio 1.0
+ * standard (and PCI standard).
+ */
+static void init_pci_config(struct pci_config *pci, u16 type,
+ u8 class, u8 subclass)
+{
+ size_t bar_offset, bar_len;
+
+ /*
+ * 4.1.4.4.1:
+ *
+ * The device MUST either present notify_off_multiplier as an even
+ * power of 2, or present notify_off_multiplier as 0.
+ *
+ * 2.1.2:
+ *
+ * The device MUST initialize device status to 0 upon reset.
+ */
+ memset(pci, 0, sizeof(*pci));
+
+ /* 4.1.2.1: Devices MUST have the PCI Vendor ID 0x1AF4 */
+ pci->vendor_id = 0x1AF4;
+ /* 4.1.2.1: ... PCI Device ID calculated by adding 0x1040 ... */
+ pci->device_id = 0x1040 + type;
+
+ /*
+ * PCI have specific codes for different types of devices.
+ * Linux doesn't care, but it's a good clue for people looking
+ * at the device.
+ */
+ pci->class = class;
+ pci->subclass = subclass;
+
+ /*
+ * 4.1.2.1:
+ *
+ * Non-transitional devices SHOULD have a PCI Revision ID of 1 or
+ * higher
+ */
+ pci->revid = 1;
+
+ /*
+ * 4.1.2.1:
+ *
+ * Non-transitional devices SHOULD have a PCI Subsystem Device ID of
+ * 0x40 or higher.
+ */
+ pci->subsystem_device_id = 0x40;
+
+ /* We use our dummy interrupt controller, and irq_line is the irq */
+ pci->irq_line = devices.next_irq++;
+ pci->irq_pin = 0;
+
+ /* Support for extended capabilities. */
+ pci->status = (1 << 4);
+
+ /* Link them in. */
+ /*
+ * 4.1.4.3.1:
+ *
+ * The device MUST present at least one common configuration
+ * capability.
+ */
+ pci->capabilities = offsetof(struct pci_config, common);
+
+ /* 4.1.4.3.1 ... offset MUST be 4-byte aligned. */
+ assert(pci->capabilities % 4 == 0);
+
+ bar_offset = offsetof(struct virtio_pci_mmio, cfg);
+ bar_len = sizeof(((struct virtio_pci_mmio *)0)->cfg);
+ init_cap(&pci->common, sizeof(pci->common), VIRTIO_PCI_CAP_COMMON_CFG,
+ bar_offset, bar_len,
+ offsetof(struct pci_config, notify));
+
+ /*
+ * 4.1.4.4.1:
+ *
+ * The device MUST present at least one notification capability.
+ */
+ bar_offset += bar_len;
+ bar_len = sizeof(((struct virtio_pci_mmio *)0)->notify);
+
+ /*
+ * 4.1.4.4.1:
+ *
+ * The cap.offset MUST be 2-byte aligned.
+ */
+ assert(pci->common.cap_next % 2 == 0);
+
+ /* FIXME: Use a non-zero notify_off, for per-queue notification? */
+ /*
+ * 4.1.4.4.1:
+ *
+ * The value cap.length presented by the device MUST be at least 2 and
+ * MUST be large enough to support queue notification offsets for all
+ * supported queues in all possible configurations.
+ */
+ assert(bar_len >= 2);
+
+ init_cap(&pci->notify.cap, sizeof(pci->notify),
+ VIRTIO_PCI_CAP_NOTIFY_CFG,
+ bar_offset, bar_len,
+ offsetof(struct pci_config, isr));
+
+ bar_offset += bar_len;
+ bar_len = sizeof(((struct virtio_pci_mmio *)0)->isr);
+ /*
+ * 4.1.4.5.1:
+ *
+ * The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG
+ * capability.
+ */
+ init_cap(&pci->isr, sizeof(pci->isr),
+ VIRTIO_PCI_CAP_ISR_CFG,
+ bar_offset, bar_len,
+ offsetof(struct pci_config, cfg_access));
+
+ /*
+ * 4.1.4.7.1:
+ *
+ * The device MUST present at least one VIRTIO_PCI_CAP_PCI_CFG
+ * capability.
+ */
+ /* This doesn't have any presence in the BAR */
+ init_cap(&pci->cfg_access.cap, sizeof(pci->cfg_access),
+ VIRTIO_PCI_CAP_PCI_CFG,
+ 0, 0, 0);
+
+ bar_offset += bar_len + sizeof(((struct virtio_pci_mmio *)0)->padding);
+ assert(bar_offset == sizeof(struct virtio_pci_mmio));
+
+ /*
+ * This gets sewn in and length set in set_device_config().
+ * Some devices don't have a device configuration interface, so
+ * we never expose this if we don't call set_device_config().
+ */
+ init_cap(&pci->device, sizeof(pci->device), VIRTIO_PCI_CAP_DEVICE_CFG,
+ bar_offset, 0, 0);
+}
+
+/*
+ * This routine does all the creation and setup of a new device, but we don't
+ * actually place the MMIO region until we know the size (if any) of the
+ * device-specific config. And we don't actually start the service threads
+ * until later.
+ *
+ * See what I mean about userspace being boring?
+ */
+static struct device *new_pci_device(const char *name, u16 type,
+ u8 class, u8 subclass)
+{
+ struct device *dev = malloc(sizeof(*dev));
+
+ /* Now we populate the fields one at a time. */
+ dev->name = name;
+ dev->vq = NULL;
+ dev->running = false;
+ dev->wrote_features_ok = false;
+ dev->mmio_size = sizeof(struct virtio_pci_mmio);
+ dev->mmio = calloc(1, dev->mmio_size);
+ dev->features = (u64)1 << VIRTIO_F_VERSION_1;
+ dev->features_accepted = 0;
+
+ if (devices.device_num + 1 >= MAX_PCI_DEVICES)
+ errx(1, "Can only handle 31 PCI devices");
+
+ init_pci_config(&dev->config, type, class, subclass);
+ assert(!devices.pci[devices.device_num+1]);
+ devices.pci[++devices.device_num] = dev;
+
+ return dev;
+}
+
+/*
+ * Our first setup routine is the console. It's a fairly simple device, but
+ * UNIX tty handling makes it uglier than it could be.
+ */
+static void setup_console(void)
+{
+ struct device *dev;
+ struct virtio_console_config conf;
+
+ /* If we can save the initial standard input settings... */
+ if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
+ struct termios term = orig_term;
+ /*
+ * Then we turn off echo, line buffering and ^C etc: We want a
+ * raw input stream to the Guest.
+ */
+ term.c_lflag &= ~(ISIG|ICANON|ECHO);
+ tcsetattr(STDIN_FILENO, TCSANOW, &term);
+ }
+
+ dev = new_pci_device("console", VIRTIO_ID_CONSOLE, 0x07, 0x00);
+
+ /* We store the console state in dev->priv, and initialize it. */
+ dev->priv = malloc(sizeof(struct console_abort));
+ ((struct console_abort *)dev->priv)->count = 0;
+
+ /*
+ * The console needs two virtqueues: the input then the output. When
+ * they put something the input queue, we make sure we're listening to
+ * stdin. When they put something in the output queue, we write it to
+ * stdout.
+ */
+ add_pci_virtqueue(dev, console_input, "input");
+ add_pci_virtqueue(dev, console_output, "output");
+
+ /* We need a configuration area for the emerg_wr early writes. */
+ add_pci_feature(dev, VIRTIO_CONSOLE_F_EMERG_WRITE);
+ set_device_config(dev, &conf, sizeof(conf));
+
+ verbose("device %u: console\n", devices.device_num);
+}
+/*:*/
+
+/*M:010
+ * Inter-guest networking is an interesting area. Simplest is to have a
+ * --sharenet=<name> option which opens or creates a named pipe. This can be
+ * used to send packets to another guest in a 1:1 manner.
+ *
+ * More sophisticated is to use one of the tools developed for project like UML
+ * to do networking.
+ *
+ * Faster is to do virtio bonding in kernel. Doing this 1:1 would be
+ * completely generic ("here's my vring, attach to your vring") and would work
+ * for any traffic. Of course, namespace and permissions issues need to be
+ * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide
+ * multiple inter-guest channels behind one interface, although it would
+ * require some manner of hotplugging new virtio channels.
+ *
+ * Finally, we could use a virtio network switch in the kernel, ie. vhost.
+:*/
+
+static u32 str2ip(const char *ipaddr)
+{
+ unsigned int b[4];
+
+ if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4)
+ errx(1, "Failed to parse IP address '%s'", ipaddr);
+ return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
+}
+
+static void str2mac(const char *macaddr, unsigned char mac[6])
+{
+ unsigned int m[6];
+ if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
+ &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6)
+ errx(1, "Failed to parse mac address '%s'", macaddr);
+ mac[0] = m[0];
+ mac[1] = m[1];
+ mac[2] = m[2];
+ mac[3] = m[3];
+ mac[4] = m[4];
+ mac[5] = m[5];
+}
+
+/*
+ * This code is "adapted" from libbridge: it attaches the Host end of the
+ * network device to the bridge device specified by the command line.
+ *
+ * This is yet another James Morris contribution (I'm an IP-level guy, so I
+ * dislike bridging), and I just try not to break it.
+ */
+static void add_to_bridge(int fd, const char *if_name, const char *br_name)
+{
+ int ifidx;
+ struct ifreq ifr;
+
+ if (!*br_name)
+ errx(1, "must specify bridge name");
+
+ ifidx = if_nametoindex(if_name);
+ if (!ifidx)
+ errx(1, "interface %s does not exist!", if_name);
+
+ strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
+ ifr.ifr_name[IFNAMSIZ-1] = '\0';
+ ifr.ifr_ifindex = ifidx;
+ if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
+ err(1, "can't add %s to bridge %s", if_name, br_name);
+}
+
+/*
+ * This sets up the Host end of the network device with an IP address, brings
+ * it up so packets will flow, the copies the MAC address into the hwaddr
+ * pointer.
+ */
+static void configure_device(int fd, const char *tapif, u32 ipaddr)
+{
+ struct ifreq ifr;
+ struct sockaddr_in sin;
+
+ memset(&ifr, 0, sizeof(ifr));
+ strcpy(ifr.ifr_name, tapif);
+
+ /* Don't read these incantations. Just cut & paste them like I did! */
+ sin.sin_family = AF_INET;
+ sin.sin_addr.s_addr = htonl(ipaddr);
+ memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
+ if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
+ err(1, "Setting %s interface address", tapif);
+ ifr.ifr_flags = IFF_UP;
+ if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
+ err(1, "Bringing interface %s up", tapif);
+}
+
+static int get_tun_device(char tapif[IFNAMSIZ])
+{
+ struct ifreq ifr;
+ int vnet_hdr_sz;
+ int netfd;
+
+ /* Start with this zeroed. Messy but sure. */
+ memset(&ifr, 0, sizeof(ifr));
+
+ /*
+ * We open the /dev/net/tun device and tell it we want a tap device. A
+ * tap device is like a tun device, only somehow different. To tell
+ * the truth, I completely blundered my way through this code, but it
+ * works now!
+ */
+ netfd = open_or_die("/dev/net/tun", O_RDWR);
+ ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
+ strcpy(ifr.ifr_name, "tap%d");
+ if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
+ err(1, "configuring /dev/net/tun");
+
+ if (ioctl(netfd, TUNSETOFFLOAD,
+ TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
+ err(1, "Could not set features for tun device");
+
+ /*
+ * We don't need checksums calculated for packets coming in this
+ * device: trust us!
+ */
+ ioctl(netfd, TUNSETNOCSUM, 1);
+
+ /*
+ * In virtio before 1.0 (aka legacy virtio), we added a 16-bit
+ * field at the end of the network header iff
+ * VIRTIO_NET_F_MRG_RXBUF was negotiated. For virtio 1.0,
+ * that became the norm, but we need to tell the tun device
+ * about our expanded header (which is called
+ * virtio_net_hdr_mrg_rxbuf in the legacy system).
+ */
+ vnet_hdr_sz = sizeof(struct virtio_net_hdr_v1);
+ if (ioctl(netfd, TUNSETVNETHDRSZ, &vnet_hdr_sz) != 0)
+ err(1, "Setting tun header size to %u", vnet_hdr_sz);
+
+ memcpy(tapif, ifr.ifr_name, IFNAMSIZ);
+ return netfd;
+}
+
+/*L:195
+ * Our network is a Host<->Guest network. This can either use bridging or
+ * routing, but the principle is the same: it uses the "tun" device to inject
+ * packets into the Host as if they came in from a normal network card. We
+ * just shunt packets between the Guest and the tun device.
+ */
+static void setup_tun_net(char *arg)
+{
+ struct device *dev;
+ struct net_info *net_info = malloc(sizeof(*net_info));
+ int ipfd;
+ u32 ip = INADDR_ANY;
+ bool bridging = false;
+ char tapif[IFNAMSIZ], *p;
+ struct virtio_net_config conf;
+
+ net_info->tunfd = get_tun_device(tapif);
+
+ /* First we create a new network device. */
+ dev = new_pci_device("net", VIRTIO_ID_NET, 0x02, 0x00);
+ dev->priv = net_info;
+
+ /* Network devices need a recv and a send queue, just like console. */
+ add_pci_virtqueue(dev, net_input, "rx");
+ add_pci_virtqueue(dev, net_output, "tx");
+
+ /*
+ * We need a socket to perform the magic network ioctls to bring up the
+ * tap interface, connect to the bridge etc. Any socket will do!
+ */
+ ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
+ if (ipfd < 0)
+ err(1, "opening IP socket");
+
+ /* If the command line was --tunnet=bridge:<name> do bridging. */
+ if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
+ arg += strlen(BRIDGE_PFX);
+ bridging = true;
+ }
+
+ /* A mac address may follow the bridge name or IP address */
+ p = strchr(arg, ':');
+ if (p) {
+ str2mac(p+1, conf.mac);
+ add_pci_feature(dev, VIRTIO_NET_F_MAC);
+ *p = '\0';
+ }
+
+ /* arg is now either an IP address or a bridge name */
+ if (bridging)
+ add_to_bridge(ipfd, tapif, arg);
+ else
+ ip = str2ip(arg);
+
+ /* Set up the tun device. */
+ configure_device(ipfd, tapif, ip);
+
+ /* Expect Guest to handle everything except UFO */
+ add_pci_feature(dev, VIRTIO_NET_F_CSUM);
+ add_pci_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
+ add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
+ add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
+ add_pci_feature(dev, VIRTIO_NET_F_GUEST_ECN);
+ add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO4);
+ add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO6);
+ add_pci_feature(dev, VIRTIO_NET_F_HOST_ECN);
+ /* We handle indirect ring entries */
+ add_pci_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
+ set_device_config(dev, &conf, sizeof(conf));
+
+ /* We don't need the socket any more; setup is done. */
+ close(ipfd);
+
+ if (bridging)
+ verbose("device %u: tun %s attached to bridge: %s\n",
+ devices.device_num, tapif, arg);
+ else
+ verbose("device %u: tun %s: %s\n",
+ devices.device_num, tapif, arg);
+}
+/*:*/
+
+/* This hangs off device->priv. */
+struct vblk_info {
+ /* The size of the file. */
+ off64_t len;
+
+ /* The file descriptor for the file. */
+ int fd;
+
+};
+
+/*L:210
+ * The Disk
+ *
+ * The disk only has one virtqueue, so it only has one thread. It is really
+ * simple: the Guest asks for a block number and we read or write that position
+ * in the file.
+ *
+ * Before we serviced each virtqueue in a separate thread, that was unacceptably
+ * slow: the Guest waits until the read is finished before running anything
+ * else, even if it could have been doing useful work.
+ *
+ * We could have used async I/O, except it's reputed to suck so hard that
+ * characters actually go missing from your code when you try to use it.
+ */
+static void blk_request(struct virtqueue *vq)
+{
+ struct vblk_info *vblk = vq->dev->priv;
+ unsigned int head, out_num, in_num, wlen;
+ int ret, i;
+ u8 *in;
+ struct virtio_blk_outhdr out;
+ struct iovec iov[vq->vring.num];
+ off64_t off;
+
+ /*
+ * Get the next request, where we normally wait. It triggers the
+ * interrupt to acknowledge previously serviced requests (if any).
+ */
+ head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
+
+ /* Copy the output header from the front of the iov (adjusts iov) */
+ iov_consume(vq->dev, iov, out_num, &out, sizeof(out));
+
+ /* Find and trim end of iov input array, for our status byte. */
+ in = NULL;
+ for (i = out_num + in_num - 1; i >= out_num; i--) {
+ if (iov[i].iov_len > 0) {
+ in = iov[i].iov_base + iov[i].iov_len - 1;
+ iov[i].iov_len--;
+ break;
+ }
+ }
+ if (!in)
+ bad_driver_vq(vq, "Bad virtblk cmd with no room for status");
+
+ /*
+ * For historical reasons, block operations are expressed in 512 byte
+ * "sectors".
+ */
+ off = out.sector * 512;
+
+ if (out.type & VIRTIO_BLK_T_OUT) {
+ /*
+ * Write
+ *
+ * Move to the right location in the block file. This can fail
+ * if they try to write past end.
+ */
+ if (lseek64(vblk->fd, off, SEEK_SET) != off)
+ err(1, "Bad seek to sector %llu", out.sector);
+
+ ret = writev(vblk->fd, iov, out_num);
+ verbose("WRITE to sector %llu: %i\n", out.sector, ret);
+
+ /*
+ * Grr... Now we know how long the descriptor they sent was, we
+ * make sure they didn't try to write over the end of the block
+ * file (possibly extending it).
+ */
+ if (ret > 0 && off + ret > vblk->len) {
+ /* Trim it back to the correct length */
+ ftruncate64(vblk->fd, vblk->len);
+ /* Die, bad Guest, die. */
+ bad_driver_vq(vq, "Write past end %llu+%u", off, ret);
+ }
+
+ wlen = sizeof(*in);
+ *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
+ } else if (out.type & VIRTIO_BLK_T_FLUSH) {
+ /* Flush */
+ ret = fdatasync(vblk->fd);
+ verbose("FLUSH fdatasync: %i\n", ret);
+ wlen = sizeof(*in);
+ *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
+ } else {
+ /*
+ * Read
+ *
+ * Move to the right location in the block file. This can fail
+ * if they try to read past end.
+ */
+ if (lseek64(vblk->fd, off, SEEK_SET) != off)
+ err(1, "Bad seek to sector %llu", out.sector);
+
+ ret = readv(vblk->fd, iov + out_num, in_num);
+ if (ret >= 0) {
+ wlen = sizeof(*in) + ret;
+ *in = VIRTIO_BLK_S_OK;
+ } else {
+ wlen = sizeof(*in);
+ *in = VIRTIO_BLK_S_IOERR;
+ }
+ }
+
+ /* Finished that request. */
+ add_used(vq, head, wlen);
+}
+
+/*L:198 This actually sets up a virtual block device. */
+static void setup_block_file(const char *filename)
+{
+ struct device *dev;
+ struct vblk_info *vblk;
+ struct virtio_blk_config conf;
+
+ /* Create the device. */
+ dev = new_pci_device("block", VIRTIO_ID_BLOCK, 0x01, 0x80);
+
+ /* The device has one virtqueue, where the Guest places requests. */
+ add_pci_virtqueue(dev, blk_request, "request");
+
+ /* Allocate the room for our own bookkeeping */
+ vblk = dev->priv = malloc(sizeof(*vblk));
+
+ /* First we open the file and store the length. */
+ vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
+ vblk->len = lseek64(vblk->fd, 0, SEEK_END);
+
+ /* Tell Guest how many sectors this device has. */
+ conf.capacity = cpu_to_le64(vblk->len / 512);
+
+ /*
+ * Tell Guest not to put in too many descriptors at once: two are used
+ * for the in and out elements.
+ */
+ add_pci_feature(dev, VIRTIO_BLK_F_SEG_MAX);
+ conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
+
+ set_device_config(dev, &conf, sizeof(struct virtio_blk_config));
+
+ verbose("device %u: virtblock %llu sectors\n",
+ devices.device_num, le64_to_cpu(conf.capacity));
+}
+
+/*L:211
+ * Our random number generator device reads from /dev/urandom into the Guest's
+ * input buffers. The usual case is that the Guest doesn't want random numbers
+ * and so has no buffers although /dev/urandom is still readable, whereas
+ * console is the reverse.
+ *
+ * The same logic applies, however.
+ */
+struct rng_info {
+ int rfd;
+};
+
+static void rng_input(struct virtqueue *vq)
+{
+ int len;
+ unsigned int head, in_num, out_num, totlen = 0;
+ struct rng_info *rng_info = vq->dev->priv;
+ struct iovec iov[vq->vring.num];
+
+ /* First we need a buffer from the Guests's virtqueue. */
+ head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
+ if (out_num)
+ bad_driver_vq(vq, "Output buffers in rng?");
+
+ /*
+ * Just like the console write, we loop to cover the whole iovec.
+ * In this case, short reads actually happen quite a bit.
+ */
+ while (!iov_empty(iov, in_num)) {
+ len = readv(rng_info->rfd, iov, in_num);
+ if (len <= 0)
+ err(1, "Read from /dev/urandom gave %i", len);
+ iov_consume(vq->dev, iov, in_num, NULL, len);
+ totlen += len;
+ }
+
+ /* Tell the Guest about the new input. */
+ add_used(vq, head, totlen);
+}
+
+/*L:199
+ * This creates a "hardware" random number device for the Guest.
+ */
+static void setup_rng(void)
+{
+ struct device *dev;
+ struct rng_info *rng_info = malloc(sizeof(*rng_info));
+
+ /* Our device's private info simply contains the /dev/urandom fd. */
+ rng_info->rfd = open_or_die("/dev/urandom", O_RDONLY);
+
+ /* Create the new device. */
+ dev = new_pci_device("rng", VIRTIO_ID_RNG, 0xff, 0);
+ dev->priv = rng_info;
+
+ /* The device has one virtqueue, where the Guest places inbufs. */
+ add_pci_virtqueue(dev, rng_input, "input");
+
+ /* We don't have any configuration space */
+ no_device_config(dev);
+
+ verbose("device %u: rng\n", devices.device_num);
+}
+/* That's the end of device setup. */
+
+/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */
+static void __attribute__((noreturn)) restart_guest(void)
+{
+ unsigned int i;
+
+ /*
+ * Since we don't track all open fds, we simply close everything beyond
+ * stderr.
+ */
+ for (i = 3; i < FD_SETSIZE; i++)
+ close(i);
+
+ /* Reset all the devices (kills all threads). */
+ cleanup_devices();
+
+ execv(main_args[0], main_args);
+ err(1, "Could not exec %s", main_args[0]);
+}
+
+/*L:220
+ * Finally we reach the core of the Launcher which runs the Guest, serves
+ * its input and output, and finally, lays it to rest.
+ */
+static void __attribute__((noreturn)) run_guest(void)
+{
+ for (;;) {
+ struct lguest_pending notify;
+ int readval;
+
+ /* We read from the /dev/lguest device to run the Guest. */
+ readval = pread(lguest_fd, &notify, sizeof(notify), cpu_id);
+ if (readval == sizeof(notify)) {
+ if (notify.trap == 13) {
+ verbose("Emulating instruction at %#x\n",
+ getreg(eip));
+ emulate_insn(notify.insn);
+ } else if (notify.trap == 14) {
+ verbose("Emulating MMIO at %#x\n",
+ getreg(eip));
+ emulate_mmio(notify.addr, notify.insn);
+ } else
+ errx(1, "Unknown trap %i addr %#08x\n",
+ notify.trap, notify.addr);
+ /* ENOENT means the Guest died. Reading tells us why. */
+ } else if (errno == ENOENT) {
+ char reason[1024] = { 0 };
+ pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
+ errx(1, "%s", reason);
+ /* ERESTART means that we need to reboot the guest */
+ } else if (errno == ERESTART) {
+ restart_guest();
+ /* Anything else means a bug or incompatible change. */
+ } else
+ err(1, "Running guest failed");
+ }
+}
+/*L:240
+ * This is the end of the Launcher. The good news: we are over halfway
+ * through! The bad news: the most fiendish part of the code still lies ahead
+ * of us.
+ *
+ * Are you ready? Take a deep breath and join me in the core of the Host, in
+ * "make Host".
+:*/
+
+static struct option opts[] = {
+ { "verbose", 0, NULL, 'v' },
+ { "tunnet", 1, NULL, 't' },
+ { "block", 1, NULL, 'b' },
+ { "rng", 0, NULL, 'r' },
+ { "initrd", 1, NULL, 'i' },
+ { "username", 1, NULL, 'u' },
+ { "chroot", 1, NULL, 'c' },
+ { NULL },
+};
+static void usage(void)
+{
+ errx(1, "Usage: lguest [--verbose] "
+ "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
+ "|--block=<filename>|--initrd=<filename>]...\n"
+ "<mem-in-mb> vmlinux [args...]");
+}
+
+/*L:105 The main routine is where the real work begins: */
+int main(int argc, char *argv[])
+{
+ /* Memory, code startpoint and size of the (optional) initrd. */
+ unsigned long mem = 0, start, initrd_size = 0;
+ /* Two temporaries. */
+ int i, c;
+ /* The boot information for the Guest. */
+ struct boot_params *boot;
+ /* If they specify an initrd file to load. */
+ const char *initrd_name = NULL;
+
+ /* Password structure for initgroups/setres[gu]id */
+ struct passwd *user_details = NULL;
+
+ /* Directory to chroot to */
+ char *chroot_path = NULL;
+
+ /* Save the args: we "reboot" by execing ourselves again. */
+ main_args = argv;
+
+ /*
+ * First we initialize the device list. We remember next interrupt
+ * number to use for devices (1: remember that 0 is used by the timer).
+ */
+ devices.next_irq = 1;
+
+ /* We're CPU 0. In fact, that's the only CPU possible right now. */
+ cpu_id = 0;
+
+ /*
+ * We need to know how much memory so we can set up the device
+ * descriptor and memory pages for the devices as we parse the command
+ * line. So we quickly look through the arguments to find the amount
+ * of memory now.
+ */
+ for (i = 1; i < argc; i++) {
+ if (argv[i][0] != '-') {
+ mem = atoi(argv[i]) * 1024 * 1024;
+ /*
+ * We start by mapping anonymous pages over all of
+ * guest-physical memory range. This fills it with 0,
+ * and ensures that the Guest won't be killed when it
+ * tries to access it.
+ */
+ guest_base = map_zeroed_pages(mem / getpagesize()
+ + DEVICE_PAGES);
+ guest_limit = mem;
+ guest_max = guest_mmio = mem + DEVICE_PAGES*getpagesize();
+ break;
+ }
+ }
+
+ /* We always have a console device, and it's always device 1. */
+ setup_console();
+
+ /* The options are fairly straight-forward */
+ while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
+ switch (c) {
+ case 'v':
+ verbose = true;
+ break;
+ case 't':
+ setup_tun_net(optarg);
+ break;
+ case 'b':
+ setup_block_file(optarg);
+ break;
+ case 'r':
+ setup_rng();
+ break;
+ case 'i':
+ initrd_name = optarg;
+ break;
+ case 'u':
+ user_details = getpwnam(optarg);
+ if (!user_details)
+ err(1, "getpwnam failed, incorrect username?");
+ break;
+ case 'c':
+ chroot_path = optarg;
+ break;
+ default:
+ warnx("Unknown argument %s", argv[optind]);
+ usage();
+ }
+ }
+ /*
+ * After the other arguments we expect memory and kernel image name,
+ * followed by command line arguments for the kernel.
+ */
+ if (optind + 2 > argc)
+ usage();
+
+ verbose("Guest base is at %p\n", guest_base);
+
+ /* Initialize the (fake) PCI host bridge device. */
+ init_pci_host_bridge();
+
+ /* Now we load the kernel */
+ start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
+
+ /* Boot information is stashed at physical address 0 */
+ boot = from_guest_phys(0);
+
+ /* Map the initrd image if requested (at top of physical memory) */
+ if (initrd_name) {
+ initrd_size = load_initrd(initrd_name, mem);
+ /*
+ * These are the location in the Linux boot header where the
+ * start and size of the initrd are expected to be found.
+ */
+ boot->hdr.ramdisk_image = mem - initrd_size;
+ boot->hdr.ramdisk_size = initrd_size;
+ /* The bootloader type 0xFF means "unknown"; that's OK. */
+ boot->hdr.type_of_loader = 0xFF;
+ }
+
+ /*
+ * The Linux boot header contains an "E820" memory map: ours is a
+ * simple, single region.
+ */
+ boot->e820_entries = 1;
+ boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
+ /*
+ * The boot header contains a command line pointer: we put the command
+ * line after the boot header.
+ */
+ boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
+ /* We use a simple helper to copy the arguments separated by spaces. */
+ concat((char *)(boot + 1), argv+optind+2);
+
+ /* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */
+ boot->hdr.kernel_alignment = 0x1000000;
+
+ /* Boot protocol version: 2.07 supports the fields for lguest. */
+ boot->hdr.version = 0x207;
+
+ /* The hardware_subarch value of "1" tells the Guest it's an lguest. */
+ boot->hdr.hardware_subarch = 1;
+
+ /* Tell the entry path not to try to reload segment registers. */
+ boot->hdr.loadflags |= KEEP_SEGMENTS;
+
+ /* We tell the kernel to initialize the Guest. */
+ tell_kernel(start);
+
+ /* Ensure that we terminate if a device-servicing child dies. */
+ signal(SIGCHLD, kill_launcher);
+
+ /* If we exit via err(), this kills all the threads, restores tty. */
+ atexit(cleanup_devices);
+
+ /* If requested, chroot to a directory */
+ if (chroot_path) {
+ if (chroot(chroot_path) != 0)
+ err(1, "chroot(\"%s\") failed", chroot_path);
+
+ if (chdir("/") != 0)
+ err(1, "chdir(\"/\") failed");
+
+ verbose("chroot done\n");
+ }
+
+ /* If requested, drop privileges */
+ if (user_details) {
+ uid_t u;
+ gid_t g;
+
+ u = user_details->pw_uid;
+ g = user_details->pw_gid;
+
+ if (initgroups(user_details->pw_name, g) != 0)
+ err(1, "initgroups failed");
+
+ if (setresgid(g, g, g) != 0)
+ err(1, "setresgid failed");
+
+ if (setresuid(u, u, u) != 0)
+ err(1, "setresuid failed");
+
+ verbose("Dropping privileges completed\n");
+ }
+
+ /* Finally, run the Guest. This doesn't return. */
+ run_guest();
+}
+/*:*/
+
+/*M:999
+ * Mastery is done: you now know everything I do.
+ *
+ * But surely you have seen code, features and bugs in your wanderings which
+ * you now yearn to attack? That is the real game, and I look forward to you
+ * patching and forking lguest into the Your-Name-Here-visor.
+ *
+ * Farewell, and good coding!
+ * Rusty Russell.
+ */
diff --git a/kernel/tools/lguest/lguest.txt b/kernel/tools/lguest/lguest.txt
new file mode 100644
index 000000000..06e1f4649
--- /dev/null
+++ b/kernel/tools/lguest/lguest.txt
@@ -0,0 +1,125 @@
+ __
+ (___()'`; Rusty's Remarkably Unreliable Guide to Lguest
+ /, /` - or, A Young Coder's Illustrated Hypervisor
+ \\"--\\ http://lguest.ozlabs.org
+
+Lguest is designed to be a minimal 32-bit x86 hypervisor for the Linux kernel,
+for Linux developers and users to experiment with virtualization with the
+minimum of complexity. Nonetheless, it should have sufficient features to
+make it useful for specific tasks, and, of course, you are encouraged to fork
+and enhance it (see drivers/lguest/README).
+
+Features:
+
+- Kernel module which runs in a normal kernel.
+- Simple I/O model for communication.
+- Simple program to create new guests.
+- Logo contains cute puppies: http://lguest.ozlabs.org
+
+Developer features:
+
+- Fun to hack on.
+- No ABI: being tied to a specific kernel anyway, you can change anything.
+- Many opportunities for improvement or feature implementation.
+
+Running Lguest:
+
+- The easiest way to run lguest is to use same kernel as guest and host.
+ You can configure them differently, but usually it's easiest not to.
+
+ You will need to configure your kernel with the following options:
+
+ "Processor type and features":
+ "Paravirtualized guest support" = Y
+ "Lguest guest support" = Y
+ "High Memory Support" = off/4GB
+ "Alignment value to which kernel should be aligned" = 0x100000
+ (CONFIG_PARAVIRT=y, CONFIG_LGUEST_GUEST=y, CONFIG_HIGHMEM64G=n and
+ CONFIG_PHYSICAL_ALIGN=0x100000)
+
+ "Device Drivers":
+ "Block devices"
+ "Virtio block driver" = M/Y
+ "Network device support"
+ "Universal TUN/TAP device driver support" = M/Y
+ "Virtio network driver" = M/Y
+ (CONFIG_VIRTIO_BLK=m, CONFIG_VIRTIO_NET=m and CONFIG_TUN=m)
+
+ "Virtualization"
+ "Linux hypervisor example code" = M/Y
+ (CONFIG_LGUEST=m)
+
+- A tool called "lguest" is available in this directory: type "make"
+ to build it. If you didn't build your kernel in-tree, use "make
+ O=<builddir>".
+
+- Create or find a root disk image. There are several useful ones
+ around, such as the xm-test tiny root image at
+ http://xm-test.xensource.com/ramdisks/initrd-1.1-i386.img
+
+ For more serious work, I usually use a distribution ISO image and
+ install it under qemu, then make multiple copies:
+
+ dd if=/dev/zero of=rootfile bs=1M count=2048
+ qemu -cdrom image.iso -hda rootfile -net user -net nic -boot d
+
+ Make sure that you install a getty on /dev/hvc0 if you want to log in on the
+ console!
+
+- "modprobe lg" if you built it as a module.
+
+- Run an lguest as root:
+
+ tools/lguest/lguest 64 vmlinux --tunnet=192.168.19.1 \
+ --block=rootfile root=/dev/vda
+
+ Explanation:
+ 64: the amount of memory to use, in MB.
+
+ vmlinux: the kernel image found in the top of your build directory. You
+ can also use a standard bzImage.
+
+ --tunnet=192.168.19.1: configures a "tap" device for networking with this
+ IP address.
+
+ --block=rootfile: a file or block device which becomes /dev/vda
+ inside the guest.
+
+ root=/dev/vda: this (and anything else on the command line) are
+ kernel boot parameters.
+
+- Configuring networking. I usually have the host masquerade, using
+ "iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE" and "echo 1 >
+ /proc/sys/net/ipv4/ip_forward". In this example, I would configure
+ eth0 inside the guest at 192.168.19.2.
+
+ Another method is to bridge the tap device to an external interface
+ using --tunnet=bridge:<bridgename>, and perhaps run dhcp on the guest
+ to obtain an IP address. The bridge needs to be configured first:
+ this option simply adds the tap interface to it.
+
+ A simple example on my system:
+
+ ifconfig eth0 0.0.0.0
+ brctl addbr lg0
+ ifconfig lg0 up
+ brctl addif lg0 eth0
+ dhclient lg0
+
+ Then use --tunnet=bridge:lg0 when launching the guest.
+
+ See:
+
+ http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge
+
+ for general information on how to get bridging to work.
+
+- Random number generation. Using the --rng option will provide a
+ /dev/hwrng in the guest that will read from the host's /dev/random.
+ Use this option in conjunction with rng-tools (see ../hw_random.txt)
+ to provide entropy to the guest kernel's /dev/random.
+
+There is a helpful mailing list at http://ozlabs.org/mailman/listinfo/lguest
+
+Good luck!
+Rusty Russell rusty@rustcorp.com.au.